Nutrient inputs through submarine groundwater discharge in an embayment: A radon investigation in Daya Bay, China

Science.gov (United States)

Wang, Xuejing; Li, Hailong; Yang, Jinzhong; Zheng, Chunmiao; Zhang, Yan; An, An; Zhang, Meng; Xiao, Kai

2017-08-01

Daya Bay, a semi-closed bay of the South China Sea, is famous for its aquaculture, agriculture and tourism. Although routine environmental investigations in the bay have been conducted since the early 1980s, evaluations of submarine groundwater discharge (SGD), an important process in exchange between groundwater and coastal seawater, and its environmental impacts have never been reported. In this study, naturally occurring radon isotope (222Rn) was measured continuously at two sites (north-west and middle-east sites) and used as a tracer to estimate SGD and associated nutrient inputs into the bay. The SGD rates estimated based on the 222Rn mass balance model were, on average, 28.2 cm/d at north-west site and 30.9 cm/d at middle-east site. The large SGD rate at middle-east site may be due to the large tidal amplitude and the sandy component with high permeability in sediments. The SGD-driven nutrient fluxes, which were calculated as the product of SGD flux and the difference of nutrient concentrations between coastal groundwater and seawater, were 3.28 × 105 mol/d for dissolved nitrates (NO3-N), 5.84 × 103 mol/d for dissolved inorganic phosphorous (DIP), and 8.97 × 105 mol/d for reactive silicate (Si). These nutrient inputs are comparable to or even higher than those supplied by local rivers. In addition, these SGD-driven nutrients have a nitrogen-phosphorous ratio as high as ∼43, which may significantly affect the ecology of coastal waters and lead to frequent occurrence of harmful algal blooms.

Development of NUPREP PC Version and Input Structures for NUCIRC Single Channel Analyses

International Nuclear Information System (INIS)

Yoon, Churl; Jun, Ji Su; Park, Joo Hwan

2007-12-01

The input file for a steady-state thermal-hydraulic code NUCIRC consists of common channel input data and specific channel input data in a case of single channel analysis. Even when all the data is ready for the 380 channels' single channel analyses, it takes long time and requires enormous effort to compose an input file by hand-editing. The automatic pre-processor for this tedious job is a NUPREP code. In this study, a NUPREP PC version has been developed from the source list in the program manual of NUCIRC-MOD2.000 that is imported in a form of an execution file. In this procedure, some errors found in PC executions and lost statements are fixed accordingly. It is confirmed that the developed NUPREP code produces input file correctly for the CANDU-6 single channel analysis. Additionally, the NUCIRC input structure and data format are summarized for a single channel analysis and the input CARDs required for the creep information of aged channels are listed

Development of NUPREP PC Version and Input Structures for NUCIRC Single Channel Analyses

Energy Technology Data Exchange (ETDEWEB)

Yoon, Churl; Jun, Ji Su; Park, Joo Hwan

2007-12-15

The input file for a steady-state thermal-hydraulic code NUCIRC consists of common channel input data and specific channel input data in a case of single channel analysis. Even when all the data is ready for the 380 channels' single channel analyses, it takes long time and requires enormous effort to compose an input file by hand-editing. The automatic pre-processor for this tedious job is a NUPREP code. In this study, a NUPREP PC version has been developed from the source list in the program manual of NUCIRC-MOD2.000 that is imported in a form of an execution file. In this procedure, some errors found in PC executions and lost statements are fixed accordingly. It is confirmed that the developed NUPREP code produces input file correctly for the CANDU-6 single channel analysis. Additionally, the NUCIRC input structure and data format are summarized for a single channel analysis and the input CARDs required for the creep information of aged channels are listed.

Unimolecular Logic Gate with Classical Input by Single Gold Atoms.

Science.gov (United States)

Skidin, Dmitry; Faizy, Omid; Krüger, Justus; Eisenhut, Frank; Jancarik, Andrej; Nguyen, Khanh-Hung; Cuniberti, Gianaurelio; Gourdon, Andre; Moresco, Francesca; Joachim, Christian

2018-02-27

By a combination of solution and on-surface chemistry, we synthesized an asymmetric starphene molecule with two long anthracenyl input branches and a short naphthyl output branch on the Au(111) surface. Starting from this molecule, we could demonstrate the working principle of a single molecule NAND logic gate by selectively contacting single gold atoms by atomic manipulation to the longer branches of the molecule. The logical input "1" ("0") is defined by the interaction (noninteraction) of a gold atom with one of the input branches. The output is measured by scanning tunneling spectroscopy following the shift in energy of the electronic tunneling resonances at the end of the short branch of the molecule.

Nutrient surpluses on integrated arable farms

NARCIS (Netherlands)

Schröder, J.J.; Asperen, van P.; Dongen, van G.J.M.; Wijnands, F.G.

1996-01-01

From 1990 to 1993 nutrient fluxes were monitored on 38 private arable farms that had adopted farming strategies aiming at reduced nutrient inputs and substitution of mineral fertilizers by organic fertilizers. The nutrient surplus was defined as the difference between inputs (including inputs

Land use and nutrient inputs affect priming in Andosols of Mt. Kilimanjaro

Science.gov (United States)

Mganga, Kevin; Kuzyakov, Yakov

2015-04-01

Organic C and nutrients additions in soil can accelerate mineralisation of soil organic matter i.e. priming effects. However, only very few studies have been conducted to investigate the priming effects phenomenon in tropical Andosols. Nutrients (N, P, N+P) and 14C labelled glucose were added to Andosols from six natural and intensively used ecosystems at Mt. Kilimanjaro i.e. (1) savannah, (2) maize fields, (3) lower montane forest, (4) coffee plantation, (5) grasslands and (6) Chagga homegardens. Carbon-dioxide emissions were monitored over a 60 days incubation period. Mineralisation of glucose to 14CO2 was highest in coffee plantation and lowest in Chagga homegarden soils. Maximal and minimal mineralisation rates immediately after glucose additions were observed in lower montane forest with N+P fertilisation (9.1% ± 0.83 d -1) and in savannah with N fertilisation (0.9% ± 0.17 d -1), respectively. Glucose and nutrient additions accelerated native soil organic matter mineralisation i.e. positive priming. Chagga homegarden soils had the lowest 14CO2 emissions and incorporated the highest percent of glucose into microbial biomass. 50-60% of the 14C input was retained in soil. We attribute this mainly to the high surface area of non-crystalline constituents i.e. allophanes, present in Andosols and having very high sorption capacity for organic C. The allophanic nature of Andosols of Mt. Kilimanjaro especially under traditional Chagga homegarden agroforestry system shows great potential for providing essential environmental services, notably C sequestration. Key words: Priming Effects, Andosols, Land Use Changes, Mt. Kilimanjaro, Allophanes, Tropical Agroforestry

Effect of variable annual precipitation and nutrient input on nitrogen and phosphorus transport from two Midwestern agricultural watersheds

Science.gov (United States)

Kalkhoff, Stephen J.; Hubbard, Laura E.; Tomer, Mark D.; James, D.E.

2016-01-01

Precipitation patterns and nutrient inputs affect transport of nitrate (NO3-N) and phosphorus (TP) from Midwest watersheds. Nutrient concentrations and yields from two subsurface-drained watersheds, the Little Cobb River (LCR) in southern Minnesota and the South Fork Iowa River (SFIR) in northern Iowa, were evaluated during 1996–2007 to document relative differences in timings and amounts of nutrients transported. Both watersheds are located in the prairie pothole region, but the SFIR exhibits a longer growing season and more livestock production. The SFIR yielded significantly more NO3-N than the LCR watershed (31.2 versus 21.3 kg NO3-N ha− 1 y− 1). The SFIR watershed also yielded more TP than the LCR watershed (1.13 versus 0.51 kg TP ha− 1 yr− 1), despite greater TP concentrations in the LCR. About 65% of NO3-N and 50% of TP loads were transported during April–June, and < 20% of the annual loads were transported later in the growing season from July–September. Monthly NO3-N and TP loads peaked in April from the LCR but peaked in June from the SFIR; this difference was attributed to greater snowmelt runoff in the LCR. The annual NO3-N yield increased with increasing annual runoff at a similar rate in both watersheds, but the LCR watershed yielded less annual NO3-N than the SFIR for a similar annual runoff. These two watersheds are within 150 km of one another and have similar dominant agricultural systems, but differences in climate and cropping inputs affected amounts and timing of nutrient transport.

In situ studies with Asian clams (Carbacula fluminea) detect acid mine drainage and nutrient inputs in low-order streams

International Nuclear Information System (INIS)

Soucek, D. J.; Schmidt, T. S.; Cherry, D. S.

2001-01-01

This study evaluates the correlation between transplanted Asiatic clam and indigenous community responses to acid mine drainage and nutrient loading in first-to-third-order streams, by comparing the toxicological endpoints of clam survival and growth with benthic macro-invertebrate community indices as community responses to both acid mine drainage and nutrient loading. Clam survival was found to be positively correlated with water column pH and negatively correlated with conductivity and metal concentrations. There was also a positive correlation with the relative abundance of the macro-invertebrate Ephemeroptera, the most sensitive taxonomic group, to acid mine drainage in this watershed. No correlation was found between clam growth and acid mine drainage inputs, but there was evidence of positive correlation with nitrate concentrations and the relative abundance of collector-filterer functional feeding groups. These results suggest that clam growth is related to nutrient levels and accurately reflect benthic macro-invertebrate responses to nutrient loading. 28 refs., 5 tabs., 1 fig

Uncertainty of solute flux estimation in ungauged small streams: potential implications for input-output nutrient mass balances at stream reach scale

Directory of Open Access Journals (Sweden)

A. Butturini

2005-01-01

Full Text Available Input-output mass balances within stream reaches provide in situ estimates of stream nutrient retention/release under a wide spectrum of hydrological conditions. Providing good estimates of the mass balances for nutrients depends on precise hydrological monitoring and good chemical characterisation of stream water at the input and output ends of the stream reach. There is a need to optimise the hydrological monitoring and the frequencies of water sampling to yield precise annual mass balances, so as to avoid undue cost - high resolution monitoring and subsequent chemical analysis can be labour intensive and costly. In this paper, simulation exercises were performed using a data set created to represent the instantaneous discharge and solute dynamics at the input and output ends of a model stream reach during a one year period. At the output end, stream discharge and water chemistry were monitored continuously, while the input end was assumed to be ungauged; water sampling frequency was changed arbitrarily. Instantaneous discharge at the ungauged sampling point was estimated with an empirical power model linking the discharge to the catchment area (Hooper, 1986. The model thus substitutes for the additional gauge station. Simulations showed that 10 days was the longest chemical sampling interval which could provide reach annual mass balances of acceptable precision. Presently, the relationship between discharge and catchment area is usually assumed to be linear but simulations indicate that small departures from the linearity of this relationship could cause dramatic changes in the mass balance estimations.

Potential changes in bacterial metabolism associated with increased water temperature and nutrient inputs in tropical humic lagoons

Directory of Open Access Journals (Sweden)

Vinicius eScofield

2015-04-01

Full Text Available Temperature and nutrient concentrations regulate aquatic bacterial metabolism. However, few studies have focused on the effect of the interaction between these factors on bacterial processes, and none have been performed in tropical aquatic ecosystems. We analyzed the main and interactive effects of changes in water temperature and N and P concentrations on bacterioplankton production (BP, respiration (BR and growth efficiency (BGE in tropical coastal lagoons. We used a factorial design with 3 levels of water temperature (25, 30 and 35 °C and 4 levels of N and/or P additions (Control, N, P and NP additions in five tropical humic lagoons. When data for all lagoons were pooled together, a weak interaction was observed between the increase in water temperature and the addition of nutrients. Water temperature alone had the greatest impact on bacterial metabolism by increasing BR, decreasing BP, and decreasing BGE. An increase of 1°C lead to an increase of ~ 4% in BR, a decrease of ~ 0.9% in BP, and a decrease of ~ 4% in BGE. When data were analyzed separately, lagoons responded differently to nutrient additions depending on DOC concentration. Lagoons with lowest DOC concentrations showed the strongest responses to nutrient additions: BP increased in response to N, P and their interaction, BR increased in response to N and the interaction between N and P, and BGE was negatively affected, mainly by the interaction between N and P additions. Lagoons with the highest DOC concentrations showed almost no significant relationship with nutrient additions. Taken together, these results show that different environmental drivers impact bacterial processes at different scales. Changes of bacterial metabolism related to the increase of water temperature are consistent between lagoons, therefore their consequences can be predicted at a regional scale, while the effect of nutrient inputs is specific to different lagoons but seems to be related to the DOC

Potential changes in bacterial metabolism associated with increased water temperature and nutrient inputs in tropical humic lagoons

Science.gov (United States)

Scofield, Vinicius; Jacques, Saulo M. S.; Guimarães, Jean R. D.; Farjalla, Vinicius F.

2015-01-01

Temperature and nutrient concentrations regulate aquatic bacterial metabolism. However, few studies have focused on the effect of the interaction between these factors on bacterial processes, and none have been performed in tropical aquatic ecosystems. We analyzed the main and interactive effects of changes in water temperature and N and P concentrations on bacterioplankton production (BP), bacterioplankton respiration (BR) and bacterial growth efficiency (BGE) in tropical coastal lagoons. We used a factorial design with three levels of water temperature (25, 30, and 35°C) and four levels of N and/or P additions (Control, N, P, and NP additions) in five tropical humic lagoons. When data for all lagoons were pooled together, a weak interaction was observed between the increase in water temperature and the addition of nutrients. Water temperature alone had the greatest impact on bacterial metabolism by increasing BR, decreasing BP, and decreasing BGE. An increase of 1°C lead to an increase of ~4% in BR, a decrease of ~0.9% in BP, and a decrease of ~4% in BGE. When data were analyzed separately, lagoons responded differently to nutrient additions depending on Dissolved Organic Carbon (DOC) concentration. Lagoons with lowest DOC concentrations showed the strongest responses to nutrient additions: BP increased in response to N, P, and their interaction, BR increased in response to N and the interaction between N and P, and BGE was negatively affected, mainly by the interaction between N and P additions. Lagoons with the highest DOC concentrations showed almost no significant relationship with nutrient additions. Taken together, these results show that different environmental drivers impact bacterial processes at different scales. Changes of bacterial metabolism related to the increase of water temperature are consistent between lagoons, therefore their consequences can be predicted at a regional scale, while the effect of nutrient inputs is specific to different

Input-output balances of acids, heavy metals and nutrients, and compartments of accumulation and depletion in forest ecosystems

International Nuclear Information System (INIS)

Mayer, R.

1989-01-01

Forest damage and decline are the consequence of several stress factors acting upon forest ecosystems in various combinations and degrees. Impact of atmospheric pollutants is certainly one of the most prominent of these factors. Regional comparion is facilitated by considering groups of atmospheric substances. We distinguish: 1. Acids and acidifying substances, 2. Heavy metals and 3. Nutrients: N, P, K, Ca, Mg, S. Forest decline has to be recognized as an expression of changes within the forest ecosystem, changes which must be accompanied by a non-steady state of the material balance. The best way to investigate changes in the material balance is to look at input and output of matter to the ecosystems. A positive balance (input > output) over a period of more than one year means accumulation, negative balance (input < output) means depletion of a substance. Based upon several case studies (Subjects I, K), we come to a typification of the material balance at any individual site which is defined by the immission/deposition situation on the one hand, by the geological-pedological site characteristics on the other hand. (orig.VT)

Development of phytoplankton communities: Implications of nutrient injections on phytoplankton composition, pH and ecosystem production

DEFF Research Database (Denmark)

Jakobsen, Hans; Blanda, Elisa; Stæhr, Peter Anton

2015-01-01

The development of a marine phytoplankton community was studied in a series of mesocosm tanks exposed to different levels of nutrient inputs. Key ecosystem variables such as phytoplankton species development, ecosystem net production (NEP), pH and bacteria production were measured. The overall aim...... was to mimic the consequences of extreme weather events by applying nutrients in either repeated (pulse treatment) versus a single inputs (full treatment). Regardless of treatment type, pH increased steadily, until nutrients became exhausted. During the experiment, potentially nuisance dinoflagellates...... developed and became dominant whereas diatoms became rare as compared to the parallel controls. At pH > 9, a shift from the presence of the potential nuisance Alexandrium pseudogonyaulax towards high pH tolerant Prorocentrum species was observed. Diatoms disappeared when A. pseudogonyaulax became dominant...

A Direct Algorithm for Pole Placement by State-derivative Feedback for Single-input Linear Systems

Directory of Open Access Journals (Sweden)

Taha H. S. Abdelaziz

2003-01-01

Full Text Available This paper deals with the direct solution of the pole placement problem for single-input linear systems using state-derivative feedback. This pole placement problem is always solvable for any controllable systems if all eigenvalues of the original system are nonzero. Then any arbitrary closed-loop poles can be placed in order to achieve the desired system performance. The solving procedure results in a formula similar to the Ackermann formula. Its derivation is based on the transformation of a linear single-input system into Frobenius canonical form by a special coordinate transformation, then solving the pole placement problem by state derivative feedback. Finally the solution is extended also for single-input time-varying control systems. The simulation results are included to show the effectiveness of the proposed approach.

Effectiveness of cattail ('Typha' spp. management techniques depends on exogenous nitrogen inputs

Directory of Open Access Journals (Sweden)

Kenneth J. Elgersma

2017-05-01

Full Text Available Wetlands occupy a position in the landscape that makes them vulnerable to the effects of current land use and the legacies of past land use. Many wetlands in agricultural regions like the North American Midwest are strongly affected by elevated nutrient inputs as well as high rates of invasion by the hybrid cattail 'Typha' x 'glauca'. These two stressors also exacerbate each other: increased nutrients increase invasion success, and invasions increase nutrient retention and nutrient loads in the wetland. This interaction could create a positive feedback that would inhibit efforts to manage and control invasions, but little is known about the effects of past or present nutrient inputs on wetland invasive plant management. We augmented a previously-published community-ecosystem model (MONDRIAN to simulate the most common invasive plant management tools: burning, mowing, and herbicide application. We then simulated different management strategies and 3 different durations in low and high nutrient input conditions, and found that the most effective management strategy and duration depends strongly on the amount of nutrients entering the wetland. In high-nutrient wetlands where invasions were most successful, a combination of herbicide and fire was most effective at reducing invasion. However, in low-nutrient wetlands this approach did little to reduce invasion. A longer treatment duration (6 years was generally better than a 1-year treatment in high-nutrient wetlands, but was generally worse than the 1-year treatment in low-nutrient wetlands. At the ecosystem level, we found that management effects were relatively modest: there was little effect of management on ecosystem C storage, and while some management strategies decreased wetland nitrogen retention, this effect was transient and disappeared shortly after management ceased. Our results suggest that considering nutrient inputs in invaded wetlands can inform and improve management, and reducing

Summer inputs of riverine nutrients to the Baltic Sea: Bioavailability and eutrophication relevance

DEFF Research Database (Denmark)

Stepanauskas, R.; Jørgensen, N.O.G.; Eigaard, Ole Ritzau

2002-01-01

loading of inorganic N and P. Concentrations of total N and P ranged from 9 to 220 mumol/L and from 0.14 to 5.56 mumol/L, respectively, with the highest concentrations in the southern part of the Baltic Sea drainage area and in several rivers on the Finnish western coast. Urea and dissolved combined amino......Most nitrogen and phosphorus transported by world rivers to the oceans is associated with dissolved organic matter. However, organic matter as a potential source of N and P has hitherto been largely neglected in studies of coastal microbial food webs. We examined 50 rivers, draining a major part...... of the Baltic Sea watershed, with respect to summer concentrations, chemical composition, and biological availability of N and P. The broad spectrum of rivers studied enabled us to assess whether the input of terrigenous organic matter can be an important nutrient source, at various levels of anthropogenic...

Nutrients in the Western Wadden Sea: Freshwater Input Versus Internal Recycling

NARCIS (Netherlands)

Leote, C.; Mulder, L.; Philippart, C.J.; Epping, E.

2016-01-01

At present, phosphorus (P) is seen as the main limiting nutrient for phytoplankton growth in the western Wadden Sea. Six cruises were performed for water sampling at selected stations covering a full tidal cycle for later determination of dissolved and particulate nutrient concentrations. The major

Robust fault detection and isolation technique for single-input/single-output closed-loop control systems that exhibit actuator and sensor faults

DEFF Research Database (Denmark)

Izadi-Zamanabadi, Roozbeh; Alavi, S. M. Mahdi; Hayes, M. J.

2008-01-01

An integrated quantitative feedback design and frequency-based fault detection and isolation (FDI) approach is presented for single-input/single-output systems. A novel design methodology, based on shaping the system frequency response, is proposed to generate an appropriate residual signal...

Nutrient uptake and regeneration ratios in the Red sea with reference to the nutrient budgets

Digital Repository Service at National Institute of Oceanography (India)

Naqvi, S.W.A.; Hansen, H.P.; Kureishy, T.W.

the Red Se, however, appears to be rather uniform and the atomic ratios between carbon, nitrogen and phosphorus in the biomass are deduced to be 188:21:1. Increased input of nutrients associated with subsurface inflow of nutrient-rich waters from the Gulf...

Volcanic nutrient inputs and trophic state of Lake Caviahue, Patagonia, Argentina

Science.gov (United States)

Pedrozo, Fernando L.; Temporetti, Pedro F.; Beamud, Guadalupe; Diaz, Mónica M.

2008-12-01

The strategies for eutrophication control, remediation, and policy management are often defined for neutral to alkaline freshwater systems, as they are most suitable for human use. The influence of nutrients on eutrophication in a naturally-acidic lake is poorly known. The main purpose of the present work is to evaluate the significance of volcanic nutrients in the control of the trophic state of the acidic Lake Caviahue, located at North Patagonia, Argentina. Acidic water systems were most studied on artificial acidified lakes, such as mining lakes in Germany or pit lakes in the United States. Lake Caviahue received a very high P load (42-192 ton P/yr) and low N load (14 ton N/yr), mainly as ammonium with quite low N:P ratios (Copahue volcano represents the main natural contribution of nutrients and acidity to the Lake Caviahue. The lake is oligotrophic in terms of CHLa. Neither the transparency nor the nutrient, dissolved or particulate, contents are to date representative of the trophic state of the lake. High P loads do not imply the eutrophication of the lake. We suggest that nitrogen and not phosphorus represents the key control nutrient in volcanically acidified lakes as TON was better related to CHLa observed (0.13-0.36 mg/m 3) in the lake. The pH increased around one unit (pH 2.0-3.0) during the last five years suggesting that the lake has not yet returned to a stable state.

CMOS single-stage input-powered bridge rectifier with boost switch and duty cycle control

Science.gov (United States)

Radzuan, Roskhatijah; Mohd Salleh, Mohd Khairul; Hamzah, Mustafar Kamal; Ab Wahab, Norfishah

2017-06-01

This paper presents a single-stage input-powered bridge rectifier with boost switch for wireless-powered devices such as biomedical implants and wireless sensor nodes. Realised using CMOS process technology, it employs a duty cycle switch control to achieve high output voltage using boost technique, leading to a high output power conversion. It has only six external connections with the boost inductance. The input frequency of the bridge rectifier is set at 50 Hz, while the switching frequency is 100 kHz. The proposed circuit is fabricated on a single 0.18-micron CMOS die with a space area of 0.024 mm2. The simulated and measured results show good agreement.

Impacts of the Nutrient Inputs from Riverine on the Dynamic and Community Structure of Fungal-like Protists in the Coastal Ocean Ecosystems

Science.gov (United States)

Duan, Y.; Wang, G.; Xie, N.

2016-02-01

The coastal ocean connects terrestrial (e.g., rivers and estuaries) with oceanic ecosystems and is considered as a major component of global carbon cycles and budgets. The coastal waters are featured with a high biodiversity and high primary production. Because of the excessive primary production, a large fraction of primary organic matter becomes available to consumers as detritus in the coastal waters. Bacterioplankton have long been known to play a key role in the degradation of this detritus, and export and storage of organic matter in the coastal ecosystems. However, the primary and secondary production and the carbon biogeochemical processes in the ecosystems are largely regulated by nutrient inputs from riverine and other anthropogenic activities through heterotrophic microbial communities. Thraustochytrids, commonly known as fungal-like protists, are unicellular heterotrophic protists and are recently acknowledged to play a significant role in ocean carbon cycling. Their abundance exceeds that of bacterioplankton in the most time of the year in the coastal waters of China. Also, their abundance and diversity are largely regulated by nutrients inputs from riverine and other anthropogenic activities. Our findings support that thraustochytrids are a dominant heterotrophic microbial group in the coastal waters. Evidently, thraustochytrids are an import, but neglected, component in microbial carbon biogeochemical processes of the coastal ocean.

Graphical user interface for input output characterization of single variable and multivariable highly nonlinear systems

Directory of Open Access Journals (Sweden)

Shahrukh Adnan Khan M. D.

2017-01-01

Full Text Available This paper presents a Graphical User Interface (GUI software utility for the input/output characterization of single variable and multivariable nonlinear systems by obtaining the sinusoidal input describing function (SIDF of the plant. The software utility is developed on MATLAB R2011a environment. The developed GUI holds no restriction on the nonlinearity type, arrangement and system order; provided that output(s of the system is obtainable either though simulation or experiments. An insight to the GUI and its features are presented in this paper and example problems from both single variable and multivariable cases are demonstrated. The formulation of input/output behavior of the system is discussed and the nucleus of the MATLAB command underlying the user interface has been outlined. Some of the industries that would benefit from this software utility includes but not limited to aerospace, defense technology, robotics and automotive.

Engineering crop nutrient efficiency for sustainable agriculture.

Science.gov (United States)

Chen, Liyu; Liao, Hong

2017-10-01

Increasing crop yields can provide food, animal feed, bioenergy feedstocks and biomaterials to meet increasing global demand; however, the methods used to increase yield can negatively affect sustainability. For example, application of excess fertilizer can generate and maintain high yields but also increases input costs and contributes to environmental damage through eutrophication, soil acidification and air pollution. Improving crop nutrient efficiency can improve agricultural sustainability by increasing yield while decreasing input costs and harmful environmental effects. Here, we review the mechanisms of nutrient efficiency (primarily for nitrogen, phosphorus, potassium and iron) and breeding strategies for improving this trait, along with the role of regulation of gene expression in enhancing crop nutrient efficiency to increase yields. We focus on the importance of root system architecture to improve nutrient acquisition efficiency, as well as the contributions of mineral translocation, remobilization and metabolic efficiency to nutrient utilization efficiency. © 2017 Institute of Botany, Chinese Academy of Sciences.

ENVIRONMENTAL ACCOUNTING IN AGRICULTURE: NUTRIENT ACCOUNTING AND OTHER ASPECTS

Directory of Open Access Journals (Sweden)

P URFI

2003-04-01

Full Text Available While traditional accounting focuses on accounting for capital assets, costs, yields valued and sold in the market, environmental accounting intends to do the same with non-marketed capital assets, costs and yields, that is, externalities. The farm level nutrient balances are based on an input-output comparison, in which the nutrients entering the farm within inputs are compared to nutrients leaving the farm within the sold products. The method considers the amounts of nutrients entering the farm but not leaving it with the products to be wastes polluting the environment. The weakness of this approach is the handling of stock changes. In a farming year high amounts of nutrients contained in unsold products are not wastes, nor are they stored in the soil, but are stored in the stocks. To handle this problem the concepts of external nutrient balance and internal nutrient balance are introduced, and are tested in case studies of two Hungarian mixed farms.

Soil Fertility and Electrical Conductivity Affected by Organic Waste Rates and Nutrient Inputs

Directory of Open Access Journals (Sweden)

Davi Lopes do Carmo

2016-01-01

Full Text Available ABSTRACT The composition of organic waste (OW and its effect on soil processes may change soil fertility and electrical conductivity (EC. The side effects of waste use in crop fertilization are poorly understood for Brazilian soils. This study examined the effect of the addition of 15 different organic wastes to Oxisols and a Neosol on pH, base saturation, EC, cation exchange capacity (CEC at pH 7, and the availability of Al, macro (P, K, Ca2+, Mg2+ and S and micronutrients (B, Fe2+, Mn2+, Cu2+ and Zn2+. Soil samples (150 g were treated with chicken, pig, horse, cattle, and quail manures, sewage sludge 1 and 2, eucalyptus sawdust, plant substrate, coconut fiber, pine bark, coffee husk, peat, limed compost, and biochar. Wastes were added considering a fixed amount of C (2 g kg-1, which resulted in waste rates ranging from 2.5 to 25.6 Mg ha-1. The soil-waste mixtures were incubated for 330 days in laboratory conditions. The waste liming or acidification values were soil-dependent. The use of some manures and compost increased the pH to levels above of those considered adequate for plant growth. The soil EC was slightly increased in the Neosol and in the medium textured Oxisol, but it was sharply changed (from 195 to 394 µS cm-1 by the addition of organic wastes in the clayey Oxisol, although the EC values were below the range considered safe for plant growth. Changes in the soil availability of P, K+, Ca2+ and Zn2+ were highly related to the inputs of these nutrients by the wastes, and other factors in soil changed due to waste use. Organic waste use simultaneously affects different soil fertility attributes; thus, in addition to the target nutrient added to the soil, the soil acidity buffering capacity and the waste liming and agronomic value must be taken into account in the waste rate definition.

Above-ground biomass and nutrient accumulation in the tropical ...

African Journals Online (AJOL)

This means that the impact of logging in the Ebom rainforest remains low. However, additional research is needed on nutrient input in the forest from outside as well as on the impact of logging on nutrient leaching in order to get a complete picture of the nutrient cycles. Key-words: phytomass, nutrient pools, logging, ...

[Inventory of regional surface nutrient balance and policy recommendations in China].

Science.gov (United States)

Chen, Min-Peng; Chen, Ji-Ning

2007-06-01

By applying OECD surface soil nitrogen balance methodology, the framework, methodology and database for nutrient balance budget in China are established to evaluate the impact of nutrient balance on agricultural production and water environment. Results show that nitrogen and phosphorus surplus in China are 640 x 10(4) t and 98 x 10(4) t respectively, and nitrogen and phosphorus surplus intensity in China are 16.56 kg/hm2 and 2.53 kg/hm2 respectively. Because of striking spatial difference of nutrient balance across the country, China is seeing a dual-challenge of nutrient surplus management as well as nutrient deficit management. Chemical fertilizer and livestock manure are best targets to perform nutrient surplus management due to their marked contributions to nutrient input. However, it is not cost-effective to implement a uniform management for all regions since nutrient input structures of them vary considerably.

Optimizing nutrient management for farm systems

OpenAIRE

Goulding, Keith; Jarvis, Steve; Whitmore, Andy

2007-01-01

Increasing the inputs of nutrients has played a major role in increasing the supply of food to a continually growing world population. However, focusing attention on the most important nutrients, such as nitrogen (N), has in some cases led to nutrient imbalances, some excess applications especially of N, inefficient use and large losses to the environment with impacts on air and water quality, biodiversity and human health. In contrast, food exports from the developing to the developed world ...

Including spatial data in nutrient balance modelling on dairy farms

Science.gov (United States)

van Leeuwen, Maricke; van Middelaar, Corina; Stoof, Cathelijne; Oenema, Jouke; Stoorvogel, Jetse; de Boer, Imke

2017-04-01

The Annual Nutrient Cycle Assessment (ANCA) calculates the nitrogen (N) and phosphorus (P) balance at a dairy farm, while taking into account the subsequent nutrient cycles of the herd, manure, soil and crop components. Since January 2016, Dutch dairy farmers are required to use ANCA in order to increase understanding of nutrient flows and to minimize nutrient losses to the environment. A nutrient balance calculates the difference between nutrient inputs and outputs. Nutrients enter the farm via purchased feed, fertilizers, deposition and fixation by legumes (nitrogen), and leave the farm via milk, livestock, manure, and roughages. A positive balance indicates to which extent N and/or P are lost to the environment via gaseous emissions (N), leaching, run-off and accumulation in soil. A negative balance indicates that N and/or P are depleted from soil. ANCA was designed to calculate average nutrient flows on farm level (for the herd, manure, soil and crop components). ANCA was not designed to perform calculations of nutrient flows at the field level, as it uses averaged nutrient inputs and outputs across all fields, and it does not include field specific soil characteristics. Land management decisions, however, such as the level of N and P application, are typically taken at the field level given the specific crop and soil characteristics. Therefore the information that ANCA provides is likely not sufficient to support farmers' decisions on land management to minimize nutrient losses to the environment. This is particularly a problem when land management and soils vary between fields. For an accurate estimate of nutrient flows in a given farming system that can be used to optimize land management, the spatial scale of nutrient inputs and outputs (and thus the effect of land management and soil variation) could be essential. Our aim was to determine the effect of the spatial scale of nutrient inputs and outputs on modelled nutrient flows and nutrient use efficiencies

Fusarium spp. is able to grow and invade healthy human nails as a single source of nutrients.

Science.gov (United States)

Galletti, J; Negri, M; Grassi, F L; Kioshima-Cotica, É S; Svidzinski, T I E

2015-09-01

Onychomycosis caused by Fusarium spp. is emerging, but some factors associated with its development remain unclear, such as whether this genus is keratinolytic. The main aim of the present study was to evaluate the ability of Fusarium to use the human nail as a single source of nutrients. We also performed an epidemiological study and antifungal susceptibility testing of Fusarium spp. that were isolated from patients with onychomycosis. The epidemiological study showed that Fusarium species accounted for 12.4 % of onychomycosis cases, and it was the most common among nondermatophyte molds. The most frequent species identified were F. oxysporum (36.5 %), F. solani (31.8 %), and F. subglutinans (8.3 %). Fluconazole was not active against Fusarium spp., and the response to terbinafine varied according to species. Fusarium was able to grow in vitro without the addition of nutrients and invade healthy nails. Thus, we found that Fusarium uses keratin as a single source of nutrients, and the model proposed herein may be useful for future studies on the pathogenesis of onychomycosis.

Variability of δ15N in soil and plants at a New Zealand hill country site: correlations with soil chemistry and nutrient inputs

International Nuclear Information System (INIS)

Hawke, D.J.

2000-01-01

This study investigated 15 N enrichment and nutrient cycling in hill country used for semi-extensive pastoral agriculture, at a site where pre-European seabird breeding occurred. Soil (>15 cm) and plant samples were taken from 18 ridgeline and sideslope transects. Three stock camps (locations which grazing animals frequent) were identified within the study area, two on the ridgeline and one on the sideslope. Soil 15 N enrichment was greatest at stock camps, and lowest where stock input was minimal. Soil natural abundance 15 N (815N) was therefore an index of stock nutrient inputs. Soil δ 15 N increased with decreasing C:N ratio, consistent with N loss through volatilisation and/or nitrate leaching from net mineralisation. Plant δ 15 N from stock camps was lower than its associated soil, implying that 15 N enrichment of plant-available N was lower than that of total soil N. However, the correlation between plant δ 15 N and soil δ 15 N varied between stock camps, indicating differences in N cycling. Olsen P was higher at stock camps, although again differences were found between stock camps. Total P and N were correlated neither with stock camps nor topography, but were higher than expected from parent material concentrations and literature results, respectively. It is postulated that significant contributions of both elements from former seabird breeding remain in the soil. Copyright (2000) CSIRO Publishing

Paired single cell co-culture microenvironments isolated by two-phase flow with continuous nutrient renewal.

Science.gov (United States)

Chen, Yu-Chih; Cheng, Yu-Heng; Kim, Hong Sun; Ingram, Patrick N; Nor, Jacques E; Yoon, Euisik

2014-08-21

Cancer-stromal cell interactions are a critical process in tumorigenesis. Conventional dish-based assays, which simply mix two cell types, have limitations in three aspects: 1) limited control of the cell microenvironment; 2) inability to study cell behavior in a single-cell manner; and 3) have difficulties in characterizing single cell behavior within a highly heterogeneous cell population (e.g. tumor). An innovative use of microfluidic technology is for improving the spatial resolution for single cell assays. However, it is challenging to isolate the paired interacting cells while maintaining nutrient renewal. In this work, two-phase flow was used as a simple isolation method, separating the microenvironment of each individual chamber. As nutrients in an isolated chamber are consumed by cells, media exchange is required. To connect the cell culture chamber to the media exchange layer, we demonstrated a 3D microsystem integration technique using vertical connections fabricated by deep reactive-ion etching (DRIE). Compared to previous approaches, the presented process allows area reduction of vertical connections by an order of magnitude, enabling compact 3D integration. A semi-permeable membrane was sandwiched between the cell culture layer and the media exchange layer. The selectivity of the semi-permeable membrane results in the retention of the signaling proteins within the chamber while allowing free diffusion of nutrients (e.g., glucose and amino acids). Thus, paracrine signals are accumulated inside the chamber without cross-talk between cells in other chambers. Utilizing these innovations, we co-cultured UM-SCC-1 (head and neck squamous cell carcinoma) cells and endothelial cells to simulate tumor proliferation enhancement in the vascular endothelial niche.

SISTEM KONTROL OTOMATIK DENGAN MODEL SINGLE-INPUT-DUAL-OUTPUT DALAM KENDALI EFISIENSI UMUR-PEMAKAIAN INSTRUMEN

Directory of Open Access Journals (Sweden)

S.N.M.P. Simamora

2014-10-01

Full Text Available Efficiency condition occurs when the value of the used outputs compared to the resource total that has been used almost close to the value 1 (absolute environment. An instrument to achieve efficiency if the power output level has decreased significantly in the life of the instrument used, if it compared to the previous condition, when the instrument is not equipped with additional systems (or proposed model improvement. Even more effective if the inputs model that are used in unison to achieve a homogeneous output. On this research has been designed and implemented the automatic control system for models of single input-dual-output, wherein the sampling instruments used are lamp and fan. Source voltage used is AC (alternate-current and tested using quantitative research methods and instrumentation (with measuring instruments are observed. The results obtained demonstrate the efficiency of the instrument experienced a significant current model of single-input-dual-output applied separately instrument trials such as lamp and fan when it compared to the condition or state before. And the result show that the design has been built, can also run well.

Managed nutrient reduction impacts on nutrient concentrations, water clarity, primary production, and hypoxia in a north temperate estuary

Science.gov (United States)

Oviatt, Candace; Smith, Leslie; Krumholz, Jason; Coupland, Catherine; Stoffel, Heather; Keller, Aimee; McManus, M. Conor; Reed, Laura

2017-12-01

Except for the Providence River and side embayments like Greenwich Bay, Narragansett Bay can no longer be considered eutrophic. In summer 2012 managed nitrogen treatment in Narragansett Bay achieved a goal of reducing effluent dissolved inorganic nitrogen inputs by over 50%. Narragansett Bay represents a small northeast US estuary that had been heavily loaded with sewage effluent nutrients since the late 1800s. The input reduction was reflected in standing stock nutrients resulting in a statistically significant 60% reduction in concentration. In the Providence River estuary, total nitrogen decreased from 100 μm to about 40 μm, for example. We tested four environmental changes that might be associated with the nitrogen reduction. System apparent production was significantly decreased by 31% and 45% in the upper and mid Bay. Nutrient reductions resulted in statistically improved water clarity in the mid and upper Bay and in a 34% reduction in summer hypoxia. Nitrogen reduction also reduced the winter spring diatom bloom; winter chlorophyll levels after nutrient reduction have been significantly lower than before the reduction. The impact on the Bay will continue to evolve over the next few years and be a natural experiment for other temperate estuaries that will be experiencing nitrogen reduction. To provide perspective we review factors effecting hypoxia in other estuaries with managed nutrient reduction and conclude that, as in Narragansett Bay, physical factors can be as important as nutrients. On a positive note managed nutrient reduction has mitigated further deterioration in most estuaries.

Noise Analysis of Single-Ended Input Differential Amplifier using Stochastic Differential Equation

OpenAIRE

Tarun Kumar Rawat; Abhirup Lahiri; Ashish Gupta

2008-01-01

In this paper, we analyze the effect of noise in a single- ended input differential amplifier working at high frequencies. Both extrinsic and intrinsic noise are analyzed using time domain method employing techniques from stochastic calculus. Stochastic differential equations are used to obtain autocorrelation functions of the output noise voltage and other solution statistics like mean and variance. The analysis leads to important design implications and suggests changes in the device parame...

Minimum Symbol Error Rate Detection in Single-Input Multiple-Output Channels with Markov Noise

DEFF Research Database (Denmark)

Christensen, Lars P.B.

2005-01-01

Minimum symbol error rate detection in Single-Input Multiple- Output(SIMO) channels with Markov noise is presented. The special case of zero-mean Gauss-Markov noise is examined closer as it only requires knowledge of the second-order moments. In this special case, it is shown that optimal detection...

Nutrient Mass Balance for the Mobile River Basin in Alabama, Georgia, and Mississippi

Science.gov (United States)

Harned, D. A.; Harvill, J. S.; McMahon, G.

2001-12-01

The source and fate of nutrients in the Mobile River drainage basin are important water-quality concerns in Alabama, Georgia, and Mississippi. Land cover in the basin is 74 percent forested, 16 percent agricultural, 2.5 percent developed, and 4 percent wetland. A nutrient mass balance calculated for 18 watersheds in the Mobile River Basin indicates that agricultural non-point nitrogen and phosphorus sources and urban non-point nitrogen sources are the most important factors associated with nutrients in the streams. Nitrogen and phosphorus inputs from atmospheric deposition, crop fertilizer, biological nitrogen fixation, animal waste, and point sources were estimated for each of the 18 drainage basins. Total basin nitrogen inputs ranged from 27 to 93 percent from atmospheric deposition (56 percent mean), 4 to 45 percent from crop fertilizer (25 percent mean), animal waste (8 percent mean), and 0.2 to 11 percent from point sources (3 percent mean). Total basin phosphorus inputs ranged from 10 to 39 percent from atmospheric deposition (26 percent mean), 7 to 51 percent from crop fertilizer (28 percent mean), 20 to 64 percent from animal waste (41 percent mean), and 0.2 to 11 percent from point sources (3 percent mean). Nutrient outputs for the watersheds were estimated by calculating instream loads and estimating nutrient uptake, or withdrawal, by crops. The difference between the total basin inputs and outputs represents nutrients that are retained or processed within the basin while moving from the point of use to the stream, or in the stream. Nitrogen output, as a percentage of the total basin nitrogen inputs, ranged from 19 to 79 percent for instream loads (35 percent mean) and from 0.01 to 32 percent for crop harvest (10 percent mean). From 53 to 87 percent (75 percent mean) of nitrogen inputs were retained within the 18 basins. Phosphorus output ranged from 9 to 29 percent for instream loads (18 percent mean) and from 0.01 to 23 percent for crop harvest (7

Rain forest nutrient cycling and productivity in response to large-scale litter manipulation.

Science.gov (United States)

Wood, Tana E; Lawrence, Deborah; Clark, Deborah A; Chazdon, Robin L

2009-01-01

Litter-induced pulses of nutrient availability could play an important role in the productivity and nutrient cycling of forested ecosystems, especially tropical forests. Tropical forests experience such pulses as a result of wet-dry seasonality and during major climatic events, such as strong El Niños. We hypothesized that (1) an increase in the quantity and quality of litter inputs would stimulate leaf litter production, woody growth, and leaf litter nutrient cycling, and (2) the timing and magnitude of this response would be influenced by soil fertility and forest age. To test these hypotheses in a Costa Rican wet tropical forest, we established a large-scale litter manipulation experiment in two secondary forest sites and four old-growth forest sites of differing soil fertility. In replicated plots at each site, leaves and twigs (forest floor. We analyzed leaf litter mass, [N] and [P], and N and P inputs for addition, removal, and control plots over a two-year period. We also evaluated basal area increment of trees in removal and addition plots. There was no response of forest productivity or nutrient cycling to litter removal; however, litter addition significantly increased leaf litter production and N and P inputs 4-5 months following litter application. Litter production increased as much as 92%, and P and N inputs as much as 85% and 156%, respectively. In contrast, litter manipulation had no significant effect on woody growth. The increase in leaf litter production and N and P inputs were significantly positively related to the total P that was applied in litter form. Neither litter treatment nor forest type influenced the temporal pattern of any of the variables measured. Thus, environmental factors such as rainfall drive temporal variability in litter and nutrient inputs, while nutrient release from decomposing litter influences the magnitude. Seasonal or annual variation in leaf litter mass, such as occurs in strong El Niño events, could positively

Three-Input Single-Output Voltage-Mode Multifunction Filter with Electronic Controllability Based on Single Commercially Available IC

Directory of Open Access Journals (Sweden)

Supachai Klungtong

2017-01-01

Full Text Available This paper presents a second-order voltage-mode filter with three inputs and single-output voltage using single commercially available IC, one resistor, and two capacitors. The used commercially available IC, called LT1228, is manufactured by Linear Technology Corporation. The proposed filter is based on parallel RLC circuit. The filter provides five output filter responses, namely, band-pass (BP, band-reject (BR, low-pass (LP, high-pass (HP, and all-pass (AP functions. The selection of each filter response can be done without the requirement of active and passive component matching condition. Furthermore, the natural frequency and quality factor are electronically controlled. Besides, the nonideal case is also investigated. The output voltage node exhibits low impedance. The experimental results can validate the theoretical analyses.

Water and nutrient budgets for Vancouver Lake, Vancouver, Washington, October 2010-October 2012

Science.gov (United States)

Sheibley, Rich W.; Foreman, James R.; Marshall, Cameron A.; Welch, Wendy B.

2014-01-01

Vancouver Lake, a large shallow lake in Clark County, near Vancouver, Washington, has been undergoing water-quality problems for decades. Recently, the biggest concern for the lake are the almost annual harmful cyanobacteria blooms that cause the lake to close for recreation for several weeks each summer. Despite decades of interest in improving the water quality of the lake, fundamental information on the timing and amount of water and nutrients entering and exiting the lake is lacking. In 2010, the U.S. Geological Survey conducted a 2-year field study to quantify water flows and nutrient loads in order to develop water and nutrient budgets for the lake. This report presents monthly and annual water and nutrient budgets from October 2010–October 2012 to identify major sources and sinks of nutrients. Lake River, a tidally influenced tributary to the lake, flows into and out of the lake almost daily and composed the greatest proportion of both the water and nutrient budgets for the lake, often at orders of magnitude greater than any other source. From the water budget, we identified precipitation, evaporation and groundwater inflow as minor components of the lake hydrologic cycle, each contributing 1 percent or less to the total water budget. Nutrient budgets were compiled monthly and annually for total nitrogen, total phosphorus, and orthophosphate; and, nitrogen loads were generally an order of magnitude greater than phosphorus loads across all sources. For total nitrogen, flow from Lake River at Felida, Washington, made up 88 percent of all inputs into the lake. For total phosphorus and orthophosphate, Lake River at Felida flowing into the lake was 91 and 76 percent of total inputs, respectively. Nutrient loads from precipitation and groundwater inflow were 1 percent or less of the total budgets. Nutrient inputs from Burnt Bridge Creek and Flushing Channel composed 12 percent of the total nitrogen budget, 8 percent of the total phosphorus budget, and 21 percent

Nutrient and Phytoplankton Analysis of a Mediterranean Coastal Area

Science.gov (United States)

Sebastiá, M. T.; Rodilla, M.

2013-01-01

Identifying and quantifying the key anthropogenic nutrient input sources are essential to adopting management measures that can target input for maximum effect in controlling the phytoplankton biomass. In this study, three systems characterized by distinctive main nutrient sources were sampled along a Mediterranean coast transect. These sources were groundwater discharge in the Ahuir area, the Serpis river discharge in the Venecia area, and a submarine wastewater outfall 1,900 m from the coast. The study area includes factors considered important in determining a coastal area as a sensitive area: it has significant nutrient sources, tourism is a major source of income in the region, and it includes an area of high water residence time (Venecia area) which is affected by the harbor facilities and by wastewater discharges. We found that in the Ahuir and the submarine wastewater outfall areas, the effects of freshwater inputs were reduced because of a greater water exchange with the oligotrophic Mediterranean waters. On the other hand, in the Venecia area, the highest levels of nutrient concentration and phytoplankton biomass were attributed to the greatest water residence time. In this enclosed area, harmful dinoflagellates were detected ( Alexandrium sp. and Dinophysis caudata). If the planned enlargement of the Gandia Harbor proceeds, it may increase the vulnerability of this system and provide the proper conditions of confinement for the dinoflagellate blooms' development. Management measures should first target phosphorus inputs as this is the most potential-limiting nutrient in the Venecia area and comes from a point source that is easier to control. Finally, we recommend that harbor environmental management plans include regular monitoring of water quality in adjacent waters to identify adverse phytoplankton community changes.

Nutrient and phytoplankton analysis of a Mediterranean coastal area.

Science.gov (United States)

Sebastiá, M T; Rodilla, M

2013-01-01

Identifying and quantifying the key anthropogenic nutrient input sources are essential to adopting management measures that can target input for maximum effect in controlling the phytoplankton biomass. In this study, three systems characterized by distinctive main nutrient sources were sampled along a Mediterranean coast transect. These sources were groundwater discharge in the Ahuir area, the Serpis river discharge in the Venecia area, and a submarine wastewater outfall 1,900 m from the coast. The study area includes factors considered important in determining a coastal area as a sensitive area: it has significant nutrient sources, tourism is a major source of income in the region, and it includes an area of high water residence time (Venecia area) which is affected by the harbor facilities and by wastewater discharges. We found that in the Ahuir and the submarine wastewater outfall areas, the effects of freshwater inputs were reduced because of a greater water exchange with the oligotrophic Mediterranean waters. On the other hand, in the Venecia area, the highest levels of nutrient concentration and phytoplankton biomass were attributed to the greatest water residence time. In this enclosed area, harmful dinoflagellates were detected (Alexandrium sp. and Dinophysis caudata). If the planned enlargement of the Gandia Harbor proceeds, it may increase the vulnerability of this system and provide the proper conditions of confinement for the dinoflagellate blooms' development. Management measures should first target phosphorus inputs as this is the most potential-limiting nutrient in the Venecia area and comes from a point source that is easier to control. Finally, we recommend that harbor environmental management plans include regular monitoring of water quality in adjacent waters to identify adverse phytoplankton community changes.

Environmental farm accounting: the case of the Dutch nutrients accounting system.

NARCIS (Netherlands)

Breembroek, J.A.; Koole, B.; Poppe, K.J.; Wossink, G.A.A.

1996-01-01

In the Netherlands bookkeeping of inputs and outputs at the level of individual farms has been selected as a new solution to control nutrient use and to tax nutrient surpluses in agriculture. At the same time, nutrient accounting presents important management information. This paper presents a

Reliability-Oriented Design and Analysis of Input Capacitors in Single-Phase Transformer-less Photovoltaic Inverters

DEFF Research Database (Denmark)

Wang, Huai; Yang, Yongheng; Blaabjerg, Frede

2013-01-01

While 99% efficiency has been reported, the target of 20 years of service time imposes new challenge to cost-effective solutions for grid-connected photovoltaic (PV) inverters. Aluminum electrolytic capacitors are the weak-link in terms of reliability and lifetime in single-phase PV systems....... A reliability-oriented design guideline is proposed in this paper for the input capacitors in single-phase transformer-less PV inverters. The guideline ensures that the service time requirement is to be accomplished under different power levels and ambient temperature profiles. The theoretical analysis has been...... demonstrated by a 1 kW single-phase PV inverter....

Energy-neutral sustainable nutrient recovery incorporated with the wastewater purification process in an enlarged microbial nutrient recovery cell

Science.gov (United States)

Sun, Dongya; Gao, Yifan; Hou, Dianxun; Zuo, Kuichang; Chen, Xi; Liang, Peng; Zhang, Xiaoyuan; Ren, Zhiyong Jason; Huang, Xia

2018-04-01

Recovery of nutrient resources from the wastewater is now an inevitable strategy to maintain the supply of both nutrient and water for our huge population. While the intensive energy consumption in conventional nutrient recovery technologies still remained as the bottleneck towards the sustainable nutrient recycle. This study proposed an enlarged microbial nutrient recovery cell (EMNRC) which was powered by the energy contained in wastewater and achieved multi-cycle nutrient recovery incorporated with in situ wastewater treatment. With the optimal recovery solution of 3 g/L NaCl and the optimal volume ratio of wastewater to recovery solution of 10:1, >89% of phosphorus and >62% of ammonium nitrogen were recovered into struvite. An extremely low water input ratio of water. It was proved the EMNRC system was a promising technology which could utilize the chemical energy contained in wastewater itself and energy-neutrally recover nutrient during the continuous wastewater purification process.

Convergent responses of nitrogen and phosphorus resorption to nitrogen inputs in a semiarid grassland

Science.gov (United States)

Lü, Xiao-Tao; Reed, Sasha; Yu, Qiang; He, Nian-Peng; Wang, Zheng-Wen; Han, Xing-Guo

2013-01-01

Human activities have significantly altered nitrogen (N) availability in most terrestrial ecosystems, with consequences for community composition and ecosystem functioning. Although studies of how changes in N availability affect biodiversity and community composition are relatively common, much less remains known about the effects of N inputs on the coupled biogeochemical cycling of N and phosphorus (P), and still fewer data exist regarding how increased N inputs affect the internal cycling of these two elements in plants. Nutrient resorption is an important driver of plant nutrient economies and of the quality of litter plants produce. Accordingly, resorption patterns have marked ecological implications for plant population and community fitness, as well as for ecosystem nutrient cycling. In a semiarid grassland in northern China, we studied the effects of a wide range of N inputs on foliar nutrient resorption of two dominant grasses, Leymus chinensis and Stipa grandis. After 4 years of treatments, N and P availability in soil and N and P concentrations in green and senesced grass leaves increased with increasing rates of N addition. Foliar N and P resorption significantly decreased along the N addition gradient, implying a resorption-mediated, positive plant–soil feedback induced by N inputs. Furthermore, N : P resorption ratios were negatively correlated with the rates of N addition, indicating the sensitivity of plant N and P stoichiometry to N inputs. Taken together, the results demonstrate that N additions accelerate ecosystem uptake and turnover of both N and P in the temperate steppe and that N and P cycles are coupled in dynamic ways. The convergence of N and P resorption in response to N inputs emphasizes the importance of nutrient resorption as a pathway by which plants and ecosystems adjust in the face of increasing N availability.

Modelling concept of lettuce breeding for nutrient efficiency

NARCIS (Netherlands)

Kerbiriou, P.J.; Stomph, T.J.; Lammerts Van Bueren, E.; Struik, P.C.

2014-01-01

Modern lettuce cultivars are bred for use under high levels of input of water and nutrients, and therefore less adapted to low-input or organic conditions in which nitrate availability varies over time and within the soil profile. To create robust cultivars it is necessary to assess which traits

Nutrient delivery to Lake Winnipeg from the Red-Assiniboine River Basin – A binational application of the SPARROW model

Science.gov (United States)

Benoy, Glenn A; Jenkinson, R. Wayne; Robertson, Dale M.; Saad, David A.

2016-01-01

Excessive phosphorus (TP) and nitrogen (TN) inputs from the Red–Assiniboine River Basin (RARB) have been linked to eutrophication of Lake Winnipeg; therefore, it is important for the management of water resources to understand where and from what sources these nutrients originate. The RARB straddles the Canada–United States border and includes portions of two provinces and three states. This study represents the first binationally focused application of SPAtially Referenced Regressions on Watershed attributes (SPARROW) models to estimate loads and sources of TP and TN by jurisdiction and basin at multiple spatial scales. Major hurdles overcome to develop these models included: (1) harmonization of geospatial data sets, particularly construction of a contiguous stream network; and (2) use of novel calibration steps to accommodate limitations in spatial variability across the model extent and in the number of calibration sites. Using nutrient inputs for a 2002 base year, a RARB TP SPARROW model was calibrated that included inputs from agriculture, forests and wetlands, wastewater treatment plants (WWTPs) and stream channels, and a TN model was calibrated that included inputs from agriculture, WWTPs and atmospheric deposition. At the RARB outlet, downstream from Winnipeg, Manitoba, the majority of the delivered TP and TN came from the Red River Basin (90%), followed by the Upper Assiniboine River and Souris River basins. Agriculture was the single most important TP and TN source for each major basin, province and state. In general, stream channels (historically deposited nutrients and from bank erosion) were the second most important source of TP. Performance metrics for the RARB SPARROW model are similarly robust compared to other, larger US SPARROW models making it a potentially useful tool to address questions of where nutrients originate and their relative contributions to loads delivered to Lake Winnipeg.

High-power tests of a single-cell copper accelerating cavity driven by two input couplers

International Nuclear Information System (INIS)

Horan, D.; Bromberek, D.; Meyer, D.; Waldschmidt, G.

2008-01-01

High-power tests were conducted on a 350-MHz, single-cell copper accelerating cavity driven simultaneously by two H-loop input couplers for the purpose of determining the reliability, performance, and power-handling capability of the cavity and related components, which have routinely operated at 100-kW power levels. The test was carried out utilizing the APS 350-MHz RF Test Stand, which was modified to split the input rf power into two frac12-power feeds, each supplying power to a separate H-loop coupler on the cavity. Electromagnetic simulations of the two-coupler feed system were used to determine coupler match, peak cavity fields, and the effect of phasing errors between the coupler feed lines. The test was conducted up to a maximum total rf input power of 164-kW CW. Test apparatus details and performance data will be presented.

Strong hydrological control on nutrient cycling of subtropical rainforests

Science.gov (United States)

Lin, T. C.; Chang, C. T.; Huang, J. C.; Wang, L.; Lin, N. H.

2016-12-01

Forest nutrient cycling is strongly controlled by both biological and hydrological factors. However, based on a close examination of earlier reports, we highlight the role of hydrological control on nutrient cycling at a global scale and is more important at humid tropical and subtropical forests. we analyzed the nutrient budget of precipitation input and stream water output from 1994 to 2013 in a subtropical forest in Taiwan and conducted a data synthesis using results from 32 forests across the globe. The results revealed that monthly input and output of ions were positively correlated with water quantity, indicating hydrological control on nutrient cycling. Hydrological control is also evident from the greater ions export via stream water during the warm and wet growing season. The synthesis also illustrates that strong hydrological control leads to lower nitrogen retention and greater net loss of base cations in humid regions, particularly in the humid tropical and subtropical forests. Our result is of great significance in an era of global climate change because climate change could directly affect ecosystem nutrient cycling particularly in the tropics through changes in patterns of precipitation regime.

Influence of nutrient input on the trophic state of a tropical brackish ...

Indian Academy of Sciences (India)

water lagoon (Chilika, India), an examination of different dissolved nutrients ... toplankton biomass, was conducted through seasonal water quality monitoring in the year 2011. The ...... mortality during hypo-salinity events: A stress-induced.

Proximate and Ultimate Limiting Nutrients in the Mississippi River Plume: Implications for Hypoxia Reduction Through Nutrient Management

Science.gov (United States)

Fennel, K.; Laurent, A.

2016-02-01

A large hypoxic area (15,000 km2 on average) forms every summer over the Texas-Louisiana shelf in the northern Gulf of Mexico due to decay of organic matter that is primarily derived from nutrient inputs from the Mississippi/Atchafalaya River System. Efforts are underway to reduce the extent of hypoxic conditions through nutrient management in the watershed; for example, an interagency Hypoxia Task Force is developing Action Plans with input from various stakeholders that set out targets for hypoxia reduction. An open question is by how much nutrient loads would have to be decreased in order to produce the desired reductions in hypoxia and when these would be measurable over natural variability. We have performed a large number of multi-year nutrient load reduction scenarios with a regional biogeochemical model for the region. The model is based on the Regional Ocean Modeling System (ROMS), explicitly includes nitrogen (N) and phosphorus (P) species as inorganic nutrients, and has been shown to realistically reproduce the key processes responsible for hypoxia generation. We have quantified the effects of differential reductions in river N and P loads on hypoxic extent. An assessment of the effects of N versus P reductions is important because, thus far, nutrient management efforts have focused on N, yet P is known to limit primary production in spring and early summer. A debate is ongoing as to whether targets for P reductions should be set and whether nutrient reduction efforts should focus solely on P, which results primarily from urban and industrial point sources and is uncoupled from agricultural fertilizer application. Our results strongly indicate that N is the `ultimate' limiting nutrient to primary production determining the areal extent and duration of hypoxic conditions in a cumulative sense, while P is temporarily limiting in spring. Although reductions in river P load would decrease hypoxic extent in early summer, they would have a much smaller effect

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

Science.gov (United States)

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 soil nutrient dynamics comparison under smallholding land and farmland policy in northeast of China.

Science.gov (United States)

Ouyang, Wei; Wei, Xinfeng; Hao, Fanghua

2013-04-15

There are two kinds of land policies, the smallholding land policy (SLP) and the farmland policy (FLP) in China. The farmland nutrient dynamics under the two land policies were analysed with the soil system budget method. The averaged nitrogen (N) input of the SLP and the FLP over sixteen years increased about 23.9% and 33.3%, respectively and the phosphorus (P) input climbed about 39.1% and 42.3%, respectively. The statistical analysis showed that the land policies had significant impacts on N and P input from fertilizer and manure, but did not obviously affect the N input from seeds and biological N fixation. The efficiency percentage of N of the SLP and the FLP climbed about 54.5% and 59.4%, respectively, and the P efficiency improved by 52.7% and 82.6%, respectively. About the nutrient output, the F-test analysis indicated that the land polices had remarkable impacts on N output by crop uptake, ammonia volatilisation, denitrification, leaching and runoff, and P output by uptake, runoff, and leach. The balance showed that the absolute loss of N from land deceased about 43.6% and 46.0%, respectively, in the SLP and the FLP, and P discharge reduced about 34.2% and 75.2%, respectively. The F-test analysis of N and P efficiency and balance of between two polices both indicated that the FLP had significant impact on nutrient dynamic. With the Mitscherlich model, the correlations between nutrient input and crop uptake, usage efficiency and loss were analysed and showed that was a threshold value for the optimal nutrient input with the highest efficiency rate. For the optimal nutrient efficiency, the space for extra P addition was bigger than the N input. The FLP have more advantage than the SLP on the crop yield, nutrient efficiency and environmental discharge. Copyright © 2013 Elsevier B.V. All rights reserved.

Model analysis of riparian buffer effectiveness for reducing nutrient inputs to streams in agricultural landscapes

Science.gov (United States)

McKane, R. B.; M, S.; F, P.; Kwiatkowski, B. L.; Rastetter, E. B.

2006-12-01

Federal and state agencies responsible for protecting water quality rely mainly on statistically-based methods to assess and manage risks to the nation's streams, lakes and estuaries. Although statistical approaches provide valuable information on current trends in water quality, process-based simulation models are essential for understanding and forecasting how changes in human activities across complex landscapes impact the transport of nutrients and contaminants to surface waters. To address this need, we developed a broadly applicable, process-based watershed simulator that links a spatially-explicit hydrologic model and a terrestrial biogeochemistry model (MEL). See Stieglitz et al. and Pan et al., this meeting, for details on the design and verification of this simulator. Here we apply the watershed simulator to a generalized agricultural setting to demonstrate its potential for informing policy and management decisions concerning water quality. This demonstration specifically explores the effectiveness of riparian buffers for reducing the transport of nitrogenous fertilizers from agricultural fields to streams. The interaction of hydrologic and biogeochemical processes represented in our simulator allows several important questions to be addressed. (1) For a range of upland fertilization rates, to what extent do riparian buffers reduce nitrogen inputs to streams? (2) How does buffer effectiveness change over time as the plant-soil system approaches N-saturation? (3) How can buffers be managed to increase their effectiveness, e.g., through periodic harvest and replanting? The model results illustrate that, while the answers to these questions depend to some extent on site factors (climatic regime, soil properties and vegetation type), in all cases riparian buffers have a limited capacity to reduce nitrogen inputs to streams where fertilization rates approach those typically used for intensive agriculture (e.g., 200 kg N per ha per year for corn in the U

Streamwater chemistry and nutrient budgets for forested watersheds in New England: variability and management implications

Science.gov (United States)

J.W. Hornbeck; S.W. Bailey; D.C. Buso; J.B. Shanley

1997-01-01

Chemistry of precipitation and streamwater and resulting input-output budgets for nutrient ions were determined concurrently for three years on three upland, forested watersheds located within an 80 km radius in central New England. Chemistry of precipitation and inputs of nutrients via wet deposition were similar among the three watersheds and were generally typical...

Nutrient removal from Chinese coastal waters by large-scale seaweed aquaculture

KAUST Repository

Xiao, Xi

2017-04-21

China is facing intense coastal eutrophication. Large-scale seaweed aquaculture in China is popular, now accounting for over 2/3\\'s of global production. Here, we estimate the nutrient removal capability of large-scale Chinese seaweed farms to determine its significance in mitigating eutrophication. We combined estimates of yield and nutrient concentration of Chinese seaweed aquaculture to quantify that one hectare of seaweed aquaculture removes the equivalent nutrient inputs entering 17.8 ha for nitrogen and 126.7 ha for phosphorus of Chinese coastal waters, respectively. Chinese seaweed aquaculture annually removes approximately 75,000 t nitrogen and 9,500 t phosphorus. Whereas removal of the total N inputs to Chinese coastal waters requires a seaweed farming area 17 times larger than the extant area, one and a half times more of the seaweed area would be able to remove close to 100% of the P inputs. With the current growth rate of seaweed aquaculture, we project this industry will remove 100% of the current phosphorus inputs to Chinese coastal waters by 2026. Hence, seaweed aquaculture already plays a hitherto unrealized role in mitigating coastal eutrophication, a role that may be greatly expanded with future growth of seaweed aquaculture.

Nutrient removal from Chinese coastal waters by large-scale seaweed aquaculture

KAUST Repository

Xiao, Xi; Agusti, Susana; Lin, Fang; Li, Ke; Pan, Yaoru; Yu, Yan; Zheng, Yuhan; Wu, Jiaping; Duarte, Carlos M.

2017-01-01

China is facing intense coastal eutrophication. Large-scale seaweed aquaculture in China is popular, now accounting for over 2/3's of global production. Here, we estimate the nutrient removal capability of large-scale Chinese seaweed farms to determine its significance in mitigating eutrophication. We combined estimates of yield and nutrient concentration of Chinese seaweed aquaculture to quantify that one hectare of seaweed aquaculture removes the equivalent nutrient inputs entering 17.8 ha for nitrogen and 126.7 ha for phosphorus of Chinese coastal waters, respectively. Chinese seaweed aquaculture annually removes approximately 75,000 t nitrogen and 9,500 t phosphorus. Whereas removal of the total N inputs to Chinese coastal waters requires a seaweed farming area 17 times larger than the extant area, one and a half times more of the seaweed area would be able to remove close to 100% of the P inputs. With the current growth rate of seaweed aquaculture, we project this industry will remove 100% of the current phosphorus inputs to Chinese coastal waters by 2026. Hence, seaweed aquaculture already plays a hitherto unrealized role in mitigating coastal eutrophication, a role that may be greatly expanded with future growth of seaweed aquaculture.

Mathematical modelling of the influenced of diffusion rate on macro nutrient availability in paddy field

Science.gov (United States)

Renny; Supriyanto

2018-04-01

Nutrition is the chemical compounds that needed by the organism for the growth process. In plants, nutrients are organic or inorganic compounds that are absorbed from the roots of the soil. It consist of macro and micro nutrient. Macro nutrients are nutrition that needed by plants in large quantities, such as, nitrogen, calcium, pottacium, magnesium, and sulfur. The total soil nutrient is the difference between the input nutrient and the output nutrients. Input nutrients are nutrient that derived from the decomposition of organic substances. Meanwhile, the output nutrient consists of the nutrients that absorbed by plant roots (uptake), the evaporated nutrients (volatilized) and leached nutrients. The nutrient transport can be done through diffusion process. The diffusion process is essential in removing the nutrient from one place to the root surface. It will cause the rate of absorption of nutrient by the roots will be greater. Nutrient concept in paddy filed can be represented into a mathematical modelling, by making compartment models. The rate of concentration change in the compartment model forms a system of homogeneous linear differential equations. In this research, we will use Laplaces transformation to solve the compartment model and determined the dynamics of macro nutrition due to diffusion process.

Multi input single output model predictive control of non-linear bio-polymerization process

Energy Technology Data Exchange (ETDEWEB)

Arumugasamy, Senthil Kumar; Ahmad, Z. [School of Chemical Engineering, Univerisiti Sains Malaysia, Engineering Campus, Seri Ampangan,14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia)

2015-05-15

This paper focuses on Multi Input Single Output (MISO) Model Predictive Control of bio-polymerization process in which mechanistic model is developed and linked with the feedforward neural network model to obtain a hybrid model (Mechanistic-FANN) of lipase-catalyzed ring-opening polymerization of ε-caprolactone (ε-CL) for Poly (ε-caprolactone) production. In this research, state space model was used, in which the input to the model were the reactor temperatures and reactor impeller speeds and the output were the molecular weight of polymer (M{sub n}) and polymer polydispersity index. State space model for MISO created using System identification tool box of Matlab™. This state space model is used in MISO MPC. Model predictive control (MPC) has been applied to predict the molecular weight of the biopolymer and consequently control the molecular weight of biopolymer. The result shows that MPC is able to track reference trajectory and give optimum movement of manipulated variable.

Sewage input reduces the consumption of Rhizophora mangle propagules by crabs in a subtropical mangrove system.

Science.gov (United States)

Boehm, Frederike Ricarda; Sandrini-Neto, Leonardo; Moens, Tom; da Cunha Lana, Paulo

2016-12-01

Mangrove forests are highly productive and play a major role in global carbon cycling. Their carbon accumulation can be influenced through the consumption of nutrient-poor leaves and propagules by herbivore crabs. Anthropogenic nutrient input from sewage contamination is widespread in these often naturally nutrient-limited ecosystems. We hypothesised that sewage-mediated nutrient input to mangrove stands of Paranaguá Bay (southern Brazil), would alter the nutrient sources available for crabs, e.g. through microphytobenthos increase, and that this would reflect in their feeding behaviour. We predicted that propagules of Rhizophora mangle in contaminated stands would experience lower grazing pressure from their two main local consumers (Ucides cordatus and Goniopsis cruentata). We compared herbivory rates on R. mangle propagules in sewage contaminated and uncontaminated mangrove stands. We found that herbivory rates were significantly lower in contaminated than uncontaminated forests, but this pattern could not be clearly attributed to increased nutrient availability. Copyright © 2016 Elsevier Ltd. All rights reserved.

Proximate versus ultimate limiting nutrients in the Mississippi River Plume and Implications for Hypoxia Reductions through Nutrient Management

Science.gov (United States)

Fennel, Katja; Laurent, Arnaud

2016-04-01

A large hypoxic area (15,000 km2 on average) forms every summer over the Texas-Louisiana shelf in the northern Gulf of Mexico due to decay of organic matter that is primarily derived from nutrient inputs from the Mississippi/Atchafalaya River System. Efforts are underway to reduce the extent of hypoxic conditions through nutrient management in the watershed; for example, an interagency Hypoxia Task Force is developing Action Plans with input from various stakeholders that set out targets for hypoxia reduction. An open question is how far nutrient loads would have to be decreased in order to produce the desired reductions in hypoxia and when these would be measurable given significant natural variability. We have simulated a large number of multi-year nutrient load reduction scenarios with a regional biogeochemical model for the region. The model is based on the Regional Ocean Modeling System (ROMS), explicitly includes nitrogen (N) and phosphorus (P) species as inorganic nutrients, and has been shown to realistically reproduce the key processes responsible for hypoxia generation. We have quantified the effects of differential reductions in river N and P loads on hypoxic extent. An assessment of the effects of N versus P reductions is important because, thus far, nutrient management efforts have focused on N, yet P is known to limit primary production in spring and early summer. A debate is ongoing as to whether targets for P reductions should be set and whether nutrient reduction efforts should focus solely on P, which results primarily from urban and industrial point sources and is uncoupled from agricultural fertilizer application. Our results strongly indicate that N is the 'ultimate' limiting nutrient to primary production determining the areal extent and duration of hypoxic conditions in a cumulative sense, while P is temporarily limiting in spring. Although reductions in river P load would decrease hypoxic extent in early summer, they would have a much

Anthropogenic influences on the input and biogeochemical cycling of nutrients and mercury in Great Salt Lake, Utah, USA

Energy Technology Data Exchange (ETDEWEB)

Naftz, David [US Geological Survey, Salt Lake City 84119, UT (United States)], E-mail: dlnaftz@usgs.gov; Angeroth, Cory; Kenney, Terry [US Geological Survey, Salt Lake City 84119, UT (United States); Waddell, Bruce; Darnall, Nathan [US Fish and Wildlife Service, Salt Lake City, UT (United States); Silva, Steven [US Geological Survey, Menlo Park, CA (United States); Perschon, Clay [Utah Division of Wildlife Resources, Salt Lake City, UT (United States); Whitehead, John [Utah Department of Environmental Quality, Salt Lake City, UT (United States)

2008-06-15

Despite the ecological and economic importance of Great Salt Lake (GSL), little is known about the input and biogeochemical cycling of nutrients and trace elements in the lake. In response to increasing public concern regarding anthropogenic inputs to the GSL ecosystem, the US Geological Survey (USGS) and US Fish and Wildlife Service (USFWS) initiated coordinated studies to quantify and evaluate the significance of nutrient and Hg inputs into GSL. A 6 per mille decrease in {delta}{sup 15}N observed in brine shrimp (Artemia franciscana) samples collected from GSL during summer time periods is likely due to the consumption of cyanobacteria produced in freshwater bays entering the lake. Supporting data collected from the outflow of Farmington Bay indicates decreasing trends in {delta}{sup 15}N in particulate organic matter (POM) during the mid-summer time period, reflective of increasing proportions of cyanobacteria in algae exported to GSL on a seasonal basis. The C:N molar ratio of POM in outflow from Farmington Bay decreases during the summer period, supportive of the increased activity of N fixation indicated by decreasing {delta}{sup 15}N in brine shrimp and POM. Although N fixation is only taking place in the relatively freshwater inflows to GSL, data indicate that influx of fresh water influences large areas of the lake. Separation of GSL into two distinct hydrologic and geochemical systems from the construction of a railroad causeway in the late 1950s has created a persistent and widespread anoxic layer in the southern part of GSL. This anoxic layer, referred to as the deep brine layer (DBL), has high rates of SO{sub 4}{sup 2-} reduction, likely increasing the Hg methylation capacity. High concentrations of methyl mercury (CH{sub 3}Hg) (median concentration = 24 ng/L) were observed in the DBL with a significant proportion (31-60%) of total Hg in the CH{sub 3}Hg form. Hydroacoustic and sediment-trap evidence indicate that turbulence introduced by internal waves

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

Science.gov (United States)

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.

Soil properties and not inputs control carbon, nitrogen, phosphorus ratios in cropped soils in the long-term

Science.gov (United States)

Frossard, E.; Buchmann, N.; Bünemann, E. K.; Kiba, D. I.; Lompo, F.; Oberson, A.; Tamburini, F.; Traoré, O. Y. A.

2015-09-01

Stoichiometric approaches have been applied to understand the relationship between soil organic matter dynamics and biological nutrient transformations. However, very few studies explicitly considered the effects of agricultural management practices on soil C : N : P ratio. The aim of this study was to assess how different input types and rates would affect the C : N : P molar ratios of bulk soil, organic matter and microbial biomass in cropped soils in the long-term. Thus, we analysed the C, N and P inputs and budgets as well as soil properties in three long-term experiments established on different soil types: the Saria soil fertility trial (Burkina Faso), the Wagga Wagga rotation/stubble management/soil preparation trial (Australia), and the DOK cropping system trial (Switzerland). In each of these trials, there was a large range of C, N and P inputs which had a strong impact on element concentrations in soils. However, although C : N : P ratios of the inputs were highly variable, they had only weak effects on soil C : N : P ratios. At Saria, a positive correlation was found between the N : P ratio of inputs and microbial biomass, while no relation was observed between the nutrient ratios of inputs and soil organic matter. At Wagga Wagga, the C : P ratio of inputs was significantly correlated to total soil C : P, N : P and C : N ratios, but had no impact on the elemental composition of microbial biomass. In the DOK trial, a positive correlation was found between the C budget and the C to organic P ratio in soils, while the nutrient ratios of inputs were not related to those in the microbial biomass. We argue that these responses are due to differences in soil properties among sites. At Saria, the soil is dominated by quartz and some kaolinite, has a coarse texture, a fragile structure and a low nutrient content. Thus, microorganisms feed on inputs (plant residues, manure). In contrast, the soil at Wagga Wagga contains illite and haematite, is richer in clay and

Soil properties and not inputs control carbon : nitrogen : phosphorus ratios in cropped soils in the long term

Science.gov (United States)

Frossard, Emmanuel; Buchmann, Nina; Bünemann, Else K.; Kiba, Delwende I.; Lompo, François; Oberson, Astrid; Tamburini, Federica; Traoré, Ouakoltio Y. A.

2016-02-01

Stoichiometric approaches have been applied to understand the relationship between soil organic matter dynamics and biological nutrient transformations. However, very few studies have explicitly considered the effects of agricultural management practices on the soil C : N : P ratio. The aim of this study was to assess how different input types and rates would affect the C : N : P molar ratios of bulk soil, organic matter and microbial biomass in cropped soils in the long term. Thus, we analysed the C, N, and P inputs and budgets as well as soil properties in three long-term experiments established on different soil types: the Saria soil fertility trial (Burkina Faso), the Wagga Wagga rotation/stubble management/soil preparation trial (Australia), and the DOK (bio-Dynamic, bio-Organic, and "Konventionell") cropping system trial (Switzerland). In each of these trials, there was a large range of C, N, and P inputs which had a strong impact on element concentrations in soils. However, although C : N : P ratios of the inputs were highly variable, they had only weak effects on soil C : N : P ratios. At Saria, a positive correlation was found between the N : P ratio of inputs and microbial biomass, while no relation was observed between the nutrient ratios of inputs and soil organic matter. At Wagga Wagga, the C : P ratio of inputs was significantly correlated to total soil C : P, N : P, and C : N ratios, but had no impact on the elemental composition of microbial biomass. In the DOK trial, a positive correlation was found between the C budget and the C to organic P ratio in soils, while the nutrient ratios of inputs were not related to those in the microbial biomass. We argue that these responses are due to differences in soil properties among sites. At Saria, the soil is dominated by quartz and some kaolinite, has a coarse texture, a fragile structure, and a low nutrient content. Thus, microorganisms feed on inputs (plant residues, manure). In contrast, the soil at

PENDUGAAN NUTRIENT BUDGET TAMBAK INTENSIF UDANG, Litopenaeus vannamei

Directory of Open Access Journals (Sweden)

Rachmansyah Rachmansyah

2016-11-01

Full Text Available Penelitian ini bertujuan untuk mendapatkan nutrient budget tambak intensif udang Litopenaeus vannamei sebagai acuan alokasi input produksi pada tingkat kapasitas asimilasi lingkungan perairan. Pendugaan nutrient budget tambak udang intensif menggunakan pendekatan mass balance, dihitung berdasarkan input nutrien nitrogen - N dan fosfor – P yang berasal dari pakan, benih, pupuk, media probiotik, inflow, dan output nutrien yang ada pada produksi udang, outflow, dan endapan lumpur di dasar tambak. Sampel air, tanah, sedimen, plankton diambil sebelum penebaran dan setiap dua minggu selama pemeliharaan dari tiga petak tambak, masing-masing 5 titik sampel per petak tambak contoh. Analisis nitrogen dan fosfor dilakukan untuk sampel pakan, karkas udang awal dan akhir. Data managemen budi daya meliputi padat penebaran benur 50 ekor m-2, produksi 1.188—1.489 kg/0,25 ha, dan FCR 1,69—2,14; maka total input nutrien tambak udang Litopenaeus vannamei antara 171,9155—179,3778 (176 ± 3,9586 kgN dan 95,2533—99,4180(97,8340 ± 2,3348 kg P. Pakan mendominasi input N sebesar 61,96% ± 0,66%; disusul inflow 30,93% ± 0,70%; pupuk 6,52% ± 0,15%, serta media probiotik dan benur masing-masing <1%. Pola yang sama terjadi pada input phosphorous dengan komposisi 87,75% ± 0,24% dari pakan; 7,73% ± 0,19% pupuk; 4,05% ± 0,25% inflow dan media probiotik < 1%. Total output nitrogen tambak udang vannamei antara 107,1279-110,1438 (108,4957 ± 1,5274 kg N dan 51,6362—63,6576 (56,1292 ± 6,5604 kg P. Komposisi output nitrogen adalah outflow sebanyak 29,82% ± 3,20%; kemudian udang yang dipanen 21,32% ± 1,33%, lumpur atau sludge 10,40% ± 0,81%. Sedangkan komposisi output phosphorous didominasi oleh lumpur 39,03% ± 6,59%; kemudian udang yang dipanen 15,22% ± 0,85% dan outflow 3,09% ± 0,26%. Efisiensi pakan dan air melalui managemen budi daya yang benar menjadi peubah dominan penentu beban limbah tambak udang. This research was aimed to find out nutrient budget

Fatal attraction: vegetation responses to nutrient inputs attract herbivores to infectious anthrax carcass sites.

Science.gov (United States)

Turner, Wendy C; Kausrud, Kyrre L; Krishnappa, Yathin S; Cromsigt, Joris P G M; Ganz, Holly H; Mapaure, Isaac; Cloete, Claudine C; Havarua, Zepee; Küsters, Martina; Getz, Wayne M; Stenseth, Nils Chr

2014-11-22

Parasites can shape the foraging behaviour of their hosts through cues indicating risk of infection. When cues for risk co-occur with desired traits such as forage quality, individuals face a trade-off between nutrient acquisition and parasite exposure. We evaluated how this trade-off may influence disease transmission in a 3-year experimental study of anthrax in a guild of mammalian herbivores in Etosha National Park, Namibia. At plains zebra (Equus quagga) carcass sites we assessed (i) carcass nutrient effects on soils and grasses, (ii) concentrations of Bacillus anthracis (BA) on grasses and in soils, and (iii) herbivore grazing behaviour, compared with control sites, using motion-sensing camera traps. We found that carcass-mediated nutrient pulses improved soil and vegetation, and that BA is found on grasses up to 2 years after death. Host foraging responses to carcass sites shifted from avoidance to attraction, and ultimately to no preference, with the strength and duration of these behavioural responses varying among herbivore species. Our results demonstrate that animal carcasses alter the environment and attract grazing hosts to parasite aggregations. This attraction may enhance transmission rates, suggesting that hosts are limited in their ability to trade off nutrient intake with parasite avoidance when relying on indirect cues. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Single server queueing networks with varying service times and renewal input

Directory of Open Access Journals (Sweden)

Pierre Le Gall

2000-01-01

Full Text Available Using recent results in tandem queues and queueing networks with renewal input, when successive service times of the same customer are varying (and when the busy periods are frequently not broken up in large networks, the local queueing delay of a single server queueing network is evaluated utilizing new concepts of virtual and actual delays (respectively. It appears that because of an important property, due to the underlying tandem queue effect, the usual queueing standards (related to long queues cannot protect against significant overloads in the buffers due to some possible “agglutination phenomenon” (related to short queues. Usual network management methods and traffic simulation methods should be revised, and should monitor the partial traffic streams loads (and not only the server load.

Nutrients distribution and trophic status assessment in the northern Beibu Gulf, China

Science.gov (United States)

Lai, Junxiang; Jiang, Fajun; Ke, Ke; Xu, Mingben; Lei, Fu; Chen, Bo

2014-09-01

Using historical and 2010 field data, the distribution of nutrients in the northern Beibu Gulf of China is described. There was a decreasing trend in the concentration of nutrients from the north coast to offshore waters of the northern Beibu Gulf, reflecting the influence of inputs from land-based sources. High concentrations of dissolved inorganic nitrogen (DIN) and phosphate (PO4-P) occurred mainly at Fangchenggang Bay, Qinzhou Bay, and Lianzhou Bay. Four different methods were used to assess eutrophication. The trophic status of the Beibu Gulf was characterized using the single factor, Eutrophication index (EI), Trophic index (TRIX) and Assessment of Estuarine Trophic Status (ASSETS) methods. Based on nutrient concentrations, 73.9% of DIN and 26.7% of PO4-P samples exceeded the fourth grade Seawater Quality Standard of China. Eutrophication index values varied widely, but higher levels of eutrophication were generally found in bays and estuaries. TRIX values ranged from 2.61 to 7.27, with an average of 4.98, indicating a mesotrophic and moderately productive system. A positive correlation between TRIX and harmful algal species richness and abundance was observed. The ASSETS model evaluates eutrophication status based on a Pressure-State-Response approach, including three main indices: influencing factors, overall eutrophic condition, and future outlook. The Beibu Gulf was graded as moderate using ASSETS. The single factor and Chinese nutrient index methods were considered inadequate for the assessment of trophic status. TRIX can be used as an indicator of trophic state and ASSETS showed good potential to assess eutrophication. The results of TRIX and ASSETS depend on threshold values. To establish these values, further research is required within the northern Beibu Gulf.

A user input manual for single fuel rod behaviour analysis code FEMAXI-III

International Nuclear Information System (INIS)

Saito, Hiroaki; Yanagisawa, Kazuaki; Fujita, Misao.

1983-03-01

Principal objectives of Safety related research in connection with lighr water reactor fuel rods under normal operating condition are mainly addressed 1) to assess fuel integrity under steady state condition and 2) to generate initial condition under hypothetical accident. These assessments have to be relied principally upon steady state fuel behaviour computing code that is able to calculate fuel conditions to tbe occurred in a various manner. To achieve these objectives, efforts have been made to develope analytical computer code that calculates in-reactor fuel rod behaviour in best estimate manner. The computer code developed for the prediction of the long-term burnup response of single fuel rod under light water reactor condition is the third in a series of code versions:FEMAMI-III. The code calculates temperature, rod internal gas pressure, fission gas release and pellet-cladding interaction related rod deformation as a function of time-dependent fuel rod power and coolant boundary conditions. This document serves as a user input manual for the code FEMAMI-III which has opened to the public in year of 1982. A general description of the code input and output are included together with typical examples of input data. A detailed description of structures, analytical submodels and solution schemes in the code shall be given in the separate document to be published. (author)

Manipulating molecular quantum states with classical metal atom inputs: demonstration of a single molecule NOR logic gate.

Science.gov (United States)

Soe, We-Hyo; Manzano, Carlos; Renaud, Nicolas; de Mendoza, Paula; De Sarkar, Abir; Ample, Francisco; Hliwa, Mohamed; Echavarren, Antonio M; Chandrasekhar, Natarajan; Joachim, Christian

2011-02-22

Quantum states of a trinaphthylene molecule were manipulated by putting its naphthyl branches in contact with single Au atoms. One Au atom carries 1-bit of classical information input that is converted into quantum information throughout the molecule. The Au-trinaphthylene electronic interactions give rise to measurable energy shifts of the molecular electronic states demonstrating a NOR logic gate functionality. The NOR truth table of the single molecule logic gate was characterized by means of scanning tunnelling spectroscopy.

Long Term Large Scale river nutrient changes across the UK

Science.gov (United States)

Bell, Victoria; Naden, Pam; Tipping, Ed; Davies, Helen; Davies, Jessica; Dragosits, Ulli; Muhammed, Shibu; Quinton, John; Stuart, Marianne; Whitmore, Andy; Wu, Lianhai

2017-04-01

During recent decades and centuries, pools and fluxes of Carbon, Nitrogen and Phosphorus (C, N and P) in UK rivers and ecosystems have been transformed by the spread and fertiliser-based intensification of agriculture (necessary to sustain human populations), by atmospheric pollution, by human waste (rising in line with population growth), and now by climate change. The principal objective of the UK's NERC-funded Macronutrients LTLS research project has been to account for observable terrestrial and aquatic pools, concentrations and fluxes of C, N and P on the basis of past inputs, biotic and abiotic interactions, and transport processes. More specifically, over the last 200 years, what have been the temporal responses of plant and soil nutrient pools in different UK catchments to nutrient enrichment, and what have been the consequent effects on nutrient transfers from land to the atmosphere, freshwaters and estuaries? The work described here addresses the second question by providing an integrated quantitative description of the interlinked land and water pools and annual fluxes of C, N and P for UK catchments over time. A national-scale modelling environment has been developed, combining simple physically-based gridded models that can be parameterised using recent observations before application to long timescales. The LTLS Integrated Model (LTLS-IM) uses readily-available driving data (climate, land-use, nutrient inputs, topography), and model estimates of both terrestrial and freshwater nutrient loads have been compared with measurements from sites across the UK. Here, the focus is on the freshwater nutrient component of the LTLS-IM, but the terrestrial nutrient inputs required for this are provided by models of nutrient processes in semi-natural and agricultural systems, and from simple models of nutrients arising from human waste. In the freshwater model, lateral routing of dissolved and particulate nutrients and within-river processing such as

Nutrient additions to mitigate for loss of Pacific salmon: consequences for stream biofilm and nutrient dynamics

Science.gov (United States)

Marcarelli, Amy M.; Baxter, Colden V.; Wipfli, Mark S.

2014-01-01

Mitigation activities designed to supplement nutrient and organic matter inputs to streams experiencing decline or loss of Pacific salmon typically presuppose that an important pathway by which salmon nutrients are moved to fish (anadromous and/or resident) is via nutrient incorporation by biofilms and subsequent bottom-up stimulation of biofilm production, which is nutrient-limited in many ecosystems where salmon returns have declined. Our objective was to quantify the magnitude of nutrient incorporation and biofilm dynamics that underpin this indirect pathway in response to experimental additions of salmon carcasses and pelletized fish meal (a.k.a., salmon carcass analogs) to 500-m reaches of central Idaho streams over three years. Biofilm standing crops increased 2–8-fold and incorporated marine-derived nutrients (measured using 15N and 13C) in the month following treatment, but these responses did not persist year-to-year. Biofilms were nitrogen (N) limited before treatments, and remained N limited in analog, but not carcass-treated reaches. Despite these biofilm responses, in the month following treatment total N load was equal to 33–47% of the N added to the treated reaches, and N spiraling measurements suggested that as much as 20%, but more likely 2–3% of added N was taken up by microbes. Design of biologically and cost-effective strategies for nutrient addition will require understanding the rates at which stream microbes take up nutrients and the downstream distance traveled by exported nutrients.

Adapted breeds for organic and low input dairy systems

DEFF Research Database (Denmark)

Horn, Marco; Ferris, C; Sairanen, A

2014-01-01

Part of SOLID is to understand how contrasting genotypes adapt to a systematic restriction of nutrient and energy supply. In new studies, a number of genotypes identified as being adapted to organic and low input systems were compared with conventional breeds....

Control of cancer growth using single input autonomous fuzzy Nano-particles

Directory of Open Access Journals (Sweden)

Fahimeh Razmi

2015-04-01

Full Text Available In this paper a single input fuzzy controller is applied on autonomous drug-encapsulated nanoparticles (ADENPs to restrict the cancer growth. The proposed ADENPs, swarmly release the drug in local cancerous tissue and effectively decreases the destruction of normal tissue. The amount of released drug is defined considering to feed backed values of tumor growth rate and the used drug. Some significant characteristics of Nano particles compared to Nano-robots is their ability to recognize the cancerous tissue from the normal one and their simple structure. Nano particles became an attractive topic in Nano science and many efforts have been done to manufacture these particles. Simulation results show that the proposed controlling method not only decreases the cancerous tissue effectively but also reduces the side effects of drug impressively.

Effects of agricultural subsidies of nutrients and detritus on fish and plankton of shallow-reservoir ecosystems.

Science.gov (United States)

Pilati, Alberto; Vanni, Michael J; González, María J; Gaulke, Alicia K

2009-06-01

Agricultural activities increase exports of nutrients and sediments to lakes, with multiple potential impacts on recipient ecosystems. Nutrient inputs enhance phytoplankton and upper trophic levels, and sediment inputs can shade phytoplankton, interfere with feeding of consumers, and degrade benthic habitats. Allochthonous sediments are also a potential food source for detritivores, as is sedimenting autochthonous phytodetritus, the production of which is stimulated by nutrient inputs. We examined effects of allochthonous nutrient and sediment subsidies on fish and plankton, with special emphasis on gizzard shad (Dorosoma cepedianum). This widespread and abundant omnivorous fish has many impacts on reservoir ecosystems, including negative effects on water quality via nutrient cycling and on fisheries via competition with sportfish. Gizzard shad are most abundant in agriculturally impacted, eutrophic systems; thus, agricultural subsidies may affect reservoir food webs directly and by enhancing gizzard shad biomass. We simulated agricultural subsidies of nutrients and sediment detritus by manipulating dissolved nutrients and allochthonous detritus in a 2 x 2 factorial design in experimental ponds. Addition of nutrients alone increased primary production and biomass of zooplanktivorous fish (bluegill and young-of-year gizzard shad). Addition of allochthonous sediments alone increased algal sedimentation and decreased seston and sediment C:P ratios. Ponds receiving both nutrients and sediments showed highest levels of phytoplankton and total phosphorus. Adult and juvenile gizzard shad biomass was enhanced equally by nutrient or sediment addition, probably because this apparently P-limited detritivore ingested similar amounts of P in all subsidy treatments. Nutrient excretion rates of gizzard shad were higher in ponds with nutrient additions, where sediments were composed mainly of phytodetritus. Therefore, gizzard shad can magnify the direct effects of nutrient

Discrete Input Signaling for MISO Visible Light Communication Channels

KAUST Repository

Arfaoui, Mohamed Amine; Rezki, Zouheir; Ghrayeb, Ali; Alouini, Mohamed-Slim

2017-01-01

In this paper, we study the achievable secrecy rate of visible light communication (VLC) links for discrete input distributions. We consider single user single eavesdropper multiple-input single-output (MISO) links. In addition, both beamforming

Economic benefits of combining soil and water conservation measures with nutrient management in semiarid Burkina Faso

NARCIS (Netherlands)

Zougmoré, R.; Mando, A.; Stroosnijder, L.; Ouédraogo, E.

2004-01-01

Nutrient limitation is the main cause of per capita decline in crop production in the Sahel, where water shortage also limits an efficient use of available nutrients. Combining soil and water conservation measures with locally available nutrient inputs may optimize crop production and economic

Mariculture: significant and expanding cause of coastal nutrient enrichment

International Nuclear Information System (INIS)

Bouwman, Lex; Beusen, Arthur; Glibert, Patricia M; Overbeek, Ciska; Pawlowski, Marcin; Herrera, Jorge; Mulsow, Sandor; Yu, Rencheng; Zhou, Mingjiang

2013-01-01

Mariculture (marine aquaculture) generates nutrient waste either through the excretion by the reared organisms, or through direct enrichment by, or remineralization of, externally applied feed inputs. Importantly, the waste from fish or shellfish cannot easily be managed, as most is in dissolved form and released directly to the aquatic environment. The release of dissolved and particulate nutrients by intensive mariculture results in increasing nutrient loads (finfish and crustaceans), and changes in nutrient stoichiometry (all mariculture types). Based on different scenarios, we project that nutrients from mariculture will increase up to six fold by 2050 with exceedance of the nutrient assimilative capacity in parts of the world where mariculture growth is already rapid. Increasing nutrient loads and altered nutrient forms (increased availability of reduced relative to oxidized forms of nitrogen) and/or stoichiometric proportions (altered nitrogen:phosphorus ratios) may promote an increase in harmful algal blooms (HABs) either directly or via stimulation of algae on which mixotrophic HABs may feed. HABs can kill or intoxicate the mariculture product with severe economic losses, and can increase risks to human health. (letter)

Farmer Field School on Nutrient Management.

NARCIS (Netherlands)

Onduru, D.; Muchena, F.N.; Gachimbi, L.N.; Jager, de A.

2003-01-01

In Kenya Integrated Nutrient Management (INM) is being used to make the best use of local resources and to optimise the effects of external inputs. In Mbeere, a district that lies in the dryland area of Eastern Kenya the Farmer Field School (FFS) has been in operation during one season and work is

Differential response of carbon cycling to long-term nutrient input and altered hydrological conditions in a continental Canadian peatland

Science.gov (United States)

Berger, Sina; Praetzel, Leandra S. E.; Goebel, Marie; Blodau, Christian; Knorr, Klaus-Holger

2018-02-01

Peatlands play an important role in global carbon cycling, but their responses to long-term anthropogenically changed hydrologic conditions and nutrient infiltration are not well known. While experimental manipulation studies, e.g., fertilization or water table manipulations, exist on the plot scale, only few studies have addressed such factors under in situ conditions. Therefore, an ecological gradient from the center to the periphery of a continental Canadian peatland bordering a eutrophic water reservoir, as reflected by increasing nutrient input, enhanced water level fluctuations, and increasing coverage of vascular plants, was used for a case study of carbon cycling along a sequence of four differently altered sites. We monitored carbon dioxide (CO2) and methane (CH4) surface fluxes and dissolved inorganic carbon (DIC) and CH4 concentrations in peat profiles from April 2014 through September 2015. Moreover, we studied bulk peat and pore-water quality and we applied δ13C-CH4 and δ13C-CO2 stable isotope abundance analyses to examine dominant CH4 production and emission pathways during the growing season of 2015. We observed differential responses of carbon cycling at the four sites, presumably driven by abundances of plant functional types and vicinity to the reservoir. A shrub-dominated site in close vicinity to the reservoir was a comparably weak sink for CO2 (in 1.5 years: -1093 ± 794, in 1 year: +135 ± 281 g CO2 m-2; a net release) as compared to two graminoid-moss-dominated sites and a moss-dominated site (in 1.5 years: -1552 to -2260 g CO2 m-2, in 1 year: -896 to -1282 g CO2 m-2). Also, the shrub-dominated site featured notably low DIC pore-water concentrations and comparably 13C-enriched CH4 (δ13C- CH4: -57.81 ± 7.03 ‰) and depleted CO2 (δ13C-CO2: -15.85 ± 3.61 ‰) in a more decomposed peat, suggesting a higher share of CH4 oxidation and differences in predominant methanogenic pathways. In comparison to all other sites, the graminoid

Ia Afferent input alters the recruitment thresholds and firing rates of single human motor units.

Science.gov (United States)

Grande, G; Cafarelli, E

2003-06-01

Vibration of the patellar tendon recruits motor units in the knee extensors via excitation of muscle spindles and subsequent Ia afferent input to the alpha-motoneuron pool. Our first purpose was to determine if the recruitment threshold and firing rate of the same motor unit differed when recruited involuntarily via reflex or voluntarily via descending spinal pathways. Although Ia input is excitatory to the alpha-motoneuron pool, it has also been shown paradoxically to inhibit itself. Our second purpose was to determine if vibration of the patellar tendon during a voluntary knee extension causes a change in the firing rate of already recruited motor units. In the first protocol, 10 subjects voluntarily reproduced the same isometric force profile of the knee extensors that was elicited by vibration of the patellar tendon. Single motor unit recordings from the vastus lateralis (VL) were obtained with tungsten microelectrodes and unitary behaviour was examined during both reflex and voluntary knee extensions. Recordings from 135 single motor units showed that both recruitment thresholds and firing rates were lower during reflex contractions. In the second protocol, 7 subjects maintained a voluntary knee extension at 30 N for approximately 40-45 s. Three bursts of patellar tendon vibration were superimposed at regular intervals throughout the contraction and changes in the firing rate of already recruited motor units were examined. A total of 35 motor units were recorded and each burst of superimposed vibration caused a momentary reduction in the firing rates and recruitment of additional units. Our data provide evidence that Ia input modulates the recruitment thresholds and firing rates of motor units providing more flexibility within the neuromuscular system to grade force at low levels of force production.

Micro-Level Management of Agricultural Inputs: Emerging Approaches

Directory of Open Access Journals (Sweden)

Jonathan Weekley

2012-12-01

Full Text Available Through the development of superior plant varieties that benefit from high agrochemical inputs and irrigation, the agricultural Green Revolution has doubled crop yields, yet introduced unintended impacts on environment. An expected 50% growth in world population during the 21st century demands novel integration of advanced technologies and low-input production systems based on soil and plant biology, targeting precision delivery of inputs synchronized with growth stages of crop plants. Further, successful systems will integrate subsurface water, air and nutrient delivery, real-time soil parameter data and computer-based decision-making to mitigate plant stress and actively manipulate microbial rhizosphere communities that stimulate productivity. Such an approach will ensure food security and mitigate impacts of climate change.

Legacy nutrient dynamics and patterns of catchment response under changing land use and management

Science.gov (United States)

Attinger, S.; Van, M. K.; Basu, N. B.

2017-12-01

Watersheds are complex heterogeneous systems that store, transform, and release water and nutrients under a broad distribution of both natural and anthropogenic controls. Many current watershed models, from complex numerical models to simpler reservoir-type models, are considered to be well-developed in their ability to predict fluxes of water and nutrients to streams and groundwater. They are generally less adept, however, at capturing watershed storage dynamics. In other words, many current models are run with an assumption of steady-state dynamics, and focus on nutrient flows rather than changes in nutrient stocks within watersheds. Although these commonly used modeling approaches may be able to adequately capture short-term watershed dynamics, they are unable to represent the clear nonlinearities or hysteresis responses observed in watersheds experiencing significant changes in nutrient inputs. To address such a lack, we have, in the present work, developed a parsimonious modeling approach designed to capture long-term catchment responses to spatial and temporal changes in nutrient inputs. In this approach, we conceptualize the catchment as a biogeochemical reactor that is driven by nutrient inputs, characterized internally by both biogeochemical degradation and residence or travel time distributions, resulting in a specific nutrient output. For the model simulations, we define a range of different scenarios to represent real-world changes in land use and management implemented to improve water quality. We then introduce the concept of state-space trajectories to describe system responses to these potential changes in anthropogenic forcings. We also increase model complexity, in a stepwise fashion, by dividing the catchment into multiple biogeochemical reactors, coupled in series or in parallel. Using this approach, we attempt to answer the following questions: (1) What level of model complexity is needed to capture observed system responses? (2) How can we

Overview: Cross-habitat flux of nutrients and detritus

Science.gov (United States)

Vanni, M.J.; DeAngelis, D.L.; Schindler, D.E.; Huxel, G.R.; Polis, G.A.; Power, M.E.; Huxel, G.R.

2004-01-01

Ecologists have long known that all ecosystems receive considerable quantities of materials from outside their boundaries (e.g., Elton 1927), and quantifying the magnitude of such fluxes has long been a central tenet of ecosystem ecology (e.g., Odum 1971). Thus, one might think that the consequences of such fluxes for food webs would be well understood. However, food webs have traditionally been viewed as if they were isolated from surrounding habitats, a habit that has been particularly persistent in the modeling of food webs. When fluxes from the outside have been considered, they have largely been restricted to constant inputs directly affecting the base of the food web (e.g., solar energy or nutrients), and usually only such issues as their effects on equilibrium conditions have been considered (e.g., the well-known relationships between nutrient inputs and average densities of various food web members).

Trends in nutrients

Science.gov (United States)

Heathwaite, A.L.; Johnes, P.J.; Peters, N.E.

1996-01-01

The roles of nitrogen (N) and phosphorus (P) as key nutrients determining the trophic status of water bodies are examined, and evidence reviewed for trends in concentrations of N and P species which occur in freshwaters, primarily in northern temperate environments. Data are reported for water bodies undergoing eutrophication and acidification, especially water bodies receiving increased nitrogen inputs through the atmospheric deposition of nitrogen oxides (NOx). Nutrient loading on groundwaters and surface freshwaters is assessed with respect to causes and rates of (change, relative rates of change for N and P, and implications of change for the future management of lakes, rivers and groundwaters. In particular, the nature and emphasis of studies for N species and P fractions in lakes versus rivers and groundwaters are contrasted. This review paper primarily focuses on results from North America and Europe, particularly for the UK where a wide range of data sets exists. Few nutrient loading data have been published on water bodies in less developed countries; however, some of the available data are presented to provide a global perspective. In general, N and P concentrations have increased dramatically (>20 times background concentrations) in many areas and causes vary considerably, ranging from urbanization to changes in agricultural practices.

Limits of effective nutrient management in dairy farming: analyses of experimental farm De Marke

NARCIS (Netherlands)

Verloop, K.

2013-01-01

Key words: nutrient management, dairy, prototyping, organic matter, soil fertility, nitrogen, phosphor.

Intensive dairy production in the Netherlands is associated with high farm nutrient (N and P) inputs and high losses to the environment. The Dutch government and the dairy sector

[Nutrient use efficiency and yield-increasing effect of single basal application of rice specific controlled release fertilizer].

Science.gov (United States)

Chen, Jiansheng; Xu, Peizhi; Tang, Shuanhu; Zhang, Fabao; Xie, Chunsheng

2005-10-01

A series of pot and field experiments and field demonstrations showed that in comparing with the commonly used specific-fertilizers containing same amounts of nutrients, single basal application of rice-specific controlled release fertilizer could increase the use efficiency of N and P by 12.2% - 22.7% and 7.0% - 35.0%, respectively in pot experiment, and the use efficiency of N by 17.1% in field experiment. In 167 field demonstrations successively conducted for 3 years in various rice production areas of Guangdong Province, single basal application of the fertilizer saved the application rate of N and P by 22.1% and 21.8%, respectively, and increased the yield by 8.2%, compared with normal split fertilization.

Neural-adaptive control of single-master-multiple-slaves teleoperation for coordinated multiple mobile manipulators with time-varying communication delays and input uncertainties.

Science.gov (United States)

Li, Zhijun; Su, Chun-Yi

2013-09-01

In this paper, adaptive neural network control is investigated for single-master-multiple-slaves teleoperation in consideration of time delays and input dead-zone uncertainties for multiple mobile manipulators carrying a common object in a cooperative manner. Firstly, concise dynamics of teleoperation systems consisting of a single master robot, multiple coordinated slave robots, and the object are developed in the task space. To handle asymmetric time-varying delays in communication channels and unknown asymmetric input dead zones, the nonlinear dynamics of the teleoperation system are transformed into two subsystems through feedback linearization: local master or slave dynamics including the unknown input dead zones and delayed dynamics for the purpose of synchronization. Then, a model reference neural network control strategy based on linear matrix inequalities (LMI) and adaptive techniques is proposed. The developed control approach ensures that the defined tracking errors converge to zero whereas the coordination internal force errors remain bounded and can be made arbitrarily small. Throughout this paper, stability analysis is performed via explicit Lyapunov techniques under specific LMI conditions. The proposed adaptive neural network control scheme is robust against motion disturbances, parametric uncertainties, time-varying delays, and input dead zones, which is validated by simulation studies.

Long term continuous field survey to assess nutrient emission impact from irrigated paddy field into river catchment

Science.gov (United States)

Kogure, Kanami; Aichi, Masaatsu; Zessner, Matthias

2017-04-01

In order to achieve good river environment, it is very important to understand and to control nutrient behavior such as Nitrogen and Phosphorus. As we could reduce impact from urban and industrial activities by wastewater treatment, pollution from point sources are likely to be controlled. Besides them, nutrient emission from agricultural activity is dominant pollution source into the river system. In many countries in Asia and Africa, rice is widely cultivated and paddy field covers large areas. In Japan 54% of its arable land is occupied with irrigated paddy field. While paddy field can deteriorate river water quality due to fertilization, it is also suggested that paddy field can purify water. We carried out field survey in middle reach of the Tone River Basin with focus on a paddy field IM. The objectives of the research are 1) understanding of water and nutrient balance in paddy field, 2) data collection for assessing nutrient emission. Field survey was conducted from June 2015 to October 2016 covering two flooding seasons in summer. In our measurement, all input and output were measured regarding water, N and P to quantify water and nutrient balance in the paddy field. By measuring water quality and flow rate of inflow, outflow, infiltrating water, ground water and flooding water, we tried to quantitatively understand water, N and P cycle in a paddy field including seasonal trends, and changes accompanied with rainy events and agricultural activities like fertilization. Concerning water balance, infiltration rate was estimated by following equation. Infiltration=Irrigation water + Precipitation - Evapotranspiration -Outflow We estimated mean daily water balance during flooding season. Infiltration is 11.9mm/day in our estimation for summer in 2015. Daily water reduction depth (WRD) is sum of Evapotranspiration and Infiltration. WRD is 21.5mm/day in IM and agrees with average value in previous research. Regarding nutrient balance, we estimated an annual N and

Chemical sensors are hybrid-input memristors

Science.gov (United States)

Sysoev, V. I.; Arkhipov, V. E.; Okotrub, A. V.; Pershin, Y. V.

2018-04-01

Memristors are two-terminal electronic devices whose resistance depends on the history of input signal (voltage or current). Here we demonstrate that the chemical gas sensors can be considered as memristors with a generalized (hybrid) input, namely, with the input consisting of the voltage, analyte concentrations and applied temperature. The concept of hybrid-input memristors is demonstrated experimentally using a single-walled carbon nanotubes chemical sensor. It is shown that with respect to the hybrid input, the sensor exhibits some features common with memristors such as the hysteretic input-output characteristics. This different perspective on chemical gas sensors may open new possibilities for smart sensor applications.

Reconstruction of neuronal input through modeling single-neuron dynamics and computations

International Nuclear Information System (INIS)

Qin, Qing; Wang, Jiang; Yu, Haitao; Deng, Bin; Chan, Wai-lok

2016-01-01

Mathematical models provide a mathematical description of neuron activity, which can better understand and quantify neural computations and corresponding biophysical mechanisms evoked by stimulus. In this paper, based on the output spike train evoked by the acupuncture mechanical stimulus, we present two different levels of models to describe the input-output system to achieve the reconstruction of neuronal input. The reconstruction process is divided into two steps: First, considering the neuronal spiking event as a Gamma stochastic process. The scale parameter and the shape parameter of Gamma process are, respectively, defined as two spiking characteristics, which are estimated by a state-space method. Then, leaky integrate-and-fire (LIF) model is used to mimic the response system and the estimated spiking characteristics are transformed into two temporal input parameters of LIF model, through two conversion formulas. We test this reconstruction method by three different groups of simulation data. All three groups of estimates reconstruct input parameters with fairly high accuracy. We then use this reconstruction method to estimate the non-measurable acupuncture input parameters. Results show that under three different frequencies of acupuncture stimulus conditions, estimated input parameters have an obvious difference. The higher the frequency of the acupuncture stimulus is, the higher the accuracy of reconstruction is.

Reconstruction of neuronal input through modeling single-neuron dynamics and computations

Energy Technology Data Exchange (ETDEWEB)

Qin, Qing; Wang, Jiang; Yu, Haitao; Deng, Bin, E-mail: dengbin@tju.edu.cn; Chan, Wai-lok [School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China)

2016-06-15

Mathematical models provide a mathematical description of neuron activity, which can better understand and quantify neural computations and corresponding biophysical mechanisms evoked by stimulus. In this paper, based on the output spike train evoked by the acupuncture mechanical stimulus, we present two different levels of models to describe the input-output system to achieve the reconstruction of neuronal input. The reconstruction process is divided into two steps: First, considering the neuronal spiking event as a Gamma stochastic process. The scale parameter and the shape parameter of Gamma process are, respectively, defined as two spiking characteristics, which are estimated by a state-space method. Then, leaky integrate-and-fire (LIF) model is used to mimic the response system and the estimated spiking characteristics are transformed into two temporal input parameters of LIF model, through two conversion formulas. We test this reconstruction method by three different groups of simulation data. All three groups of estimates reconstruct input parameters with fairly high accuracy. We then use this reconstruction method to estimate the non-measurable acupuncture input parameters. Results show that under three different frequencies of acupuncture stimulus conditions, estimated input parameters have an obvious difference. The higher the frequency of the acupuncture stimulus is, the higher the accuracy of reconstruction is.

Three-input gate logic circuits on chemically assembled single-electron transistors with organic and inorganic hybrid passivation layers.

Science.gov (United States)

Majima, Yutaka; Hackenberger, Guillaume; Azuma, Yasuo; Kano, Shinya; Matsuzaki, Kosuke; Susaki, Tomofumi; Sakamoto, Masanori; Teranishi, Toshiharu

2017-01-01

Single-electron transistors (SETs) are sub-10-nm scale electronic devices based on conductive Coulomb islands sandwiched between double-barrier tunneling barriers. Chemically assembled SETs with alkanethiol-protected Au nanoparticles show highly stable Coulomb diamonds and two-input logic operations. The combination of bottom-up and top-down processes used to form the passivation layer is vital for realizing multi-gate chemically assembled SET circuits, as this combination enables us to connect conventional complementary metal oxide semiconductor (CMOS) technologies via planar processes. Here, three-input gate exclusive-OR (XOR) logic operations are demonstrated in passivated chemically assembled SETs. The passivation layer is a hybrid bilayer of self-assembled monolayers (SAMs) and pulsed laser deposited (PLD) aluminum oxide (AlO[Formula: see text]), and top-gate electrodes were prepared on the hybrid passivation layers. Top and two-side-gated SETs showed clear Coulomb oscillation and diamonds for each of the three available gates, and three-input gate XOR logic operation was clearly demonstrated. These results show the potential of chemically assembled SETs to work as logic devices with multi-gate inputs using organic and inorganic hybrid passivation layers.

Organic amendments and nutrient leaching in soil columns

Science.gov (United States)

The lack of nutrient build up in reclaimed coal mine soils would therefore require additional inputs to maintain plant productivity and establishment of a healthy ecosystem. In a greenhouse experiment, reclaimed coal mine soil were amended with fresh and composted poultry manure at the rates based ...

Tropical Andean Forests Are Highly Susceptible to Nutrient Inputs—Rapid Effects of Experimental N and P Addition to an Ecuadorian Montane Forest

Science.gov (United States)

Homeier, Jürgen; Hertel, Dietrich; Camenzind, Tessa; Cumbicus, Nixon L.; Maraun, Mark; Martinson, Guntars O.; Poma, L. Nohemy; Rillig, Matthias C.; Sandmann, Dorothee; Scheu, Stefan; Veldkamp, Edzo; Wilcke, Wolfgang; Wullaert, Hans; Leuschner, Christoph

2012-01-01

Tropical regions are facing increasing atmospheric inputs of nutrients, which will have unknown consequences for the structure and functioning of these systems. Here, we show that Neotropical montane rainforests respond rapidly to moderate additions of N (50 kg ha−1 yr−1) and P (10 kg ha−1 yr−1). Monitoring of nutrient fluxes demonstrated that the majority of added nutrients remained in the system, in either soil or vegetation. N and P additions led to not only an increase in foliar N and P concentrations, but also altered soil microbial biomass, standing fine root biomass, stem growth, and litterfall. The different effects suggest that trees are primarily limited by P, whereas some processes—notably aboveground productivity—are limited by both N and P. Highly variable and partly contrasting responses of different tree species suggest marked changes in species composition and diversity of these forests by nutrient inputs in the long term. The unexpectedly fast response of the ecosystem to moderate nutrient additions suggests high vulnerability of tropical montane forests to the expected increase in nutrient inputs. PMID:23071734

Neuronal Calcium Signaling in Metabolic Regulation and Adaptation to Nutrient Stress.

Science.gov (United States)

Jayakumar, Siddharth; Hasan, Gaiti

2018-01-01

All organisms can respond physiologically and behaviorally to environmental fluxes in nutrient levels. Different nutrient sensing pathways exist for specific metabolites, and their inputs ultimately define appropriate nutrient uptake and metabolic homeostasis. Nutrient sensing mechanisms at the cellular level require pathways such as insulin and target of rapamycin (TOR) signaling that integrates information from different organ systems like the fat body and the gut. Such integration is essential for coordinating growth with development. Here we review the role of a newly identified set of integrative interneurons and the role of intracellular calcium signaling within these neurons, in regulating nutrient sensing under conditions of nutrient stress. A comparison of the identified Drosophila circuit and cellular mechanisms employed in this circuit, with vertebrate systems, suggests that the identified cell signaling mechanisms may be conserved for neural circuit function related to nutrient sensing by central neurons. The ideas proposed are potentially relevant for understanding the molecular basis of metabolic disorders, because these are frequently linked to nutritional stress.

Effects of thermal discharges on the seasonal patterns of nutrient concentrations in brackish water

International Nuclear Information System (INIS)

Nitchals, D.

1985-05-01

Massiv quantities of water are used in power plant cooling systems, especially nuclear power plants, and are often returned to the donor ecosystem at significantly elevated temperatures. Few studies of the environmental effects of such a situation have looked extensively at the effects on nutrients in the water. The present study examined the effects of cooling water discharges from a nuclear power plant on the seasonal nutrient patterns within and outside a brackish water, research artificial lake, the 0.9 km 2 Biotest Basin on Sweden's east coast. The lack of ice cover in winter is the most apparent effect. In a portion of the lake with a relatively long water residence time, on the order of a few days, the vernal nutrient depletion of phosphate, nitrate, and nitrite apparently began sooner than outside the lake. Benthic influence on nutrient concentrations in the free water mass may be very significant in coastal areas receiving heat inputs. This study's data apparently support the conclusion by other researchers that phosphorus may be the nutrient limiting algal growth in the spring in this area of the central Baltic Sea. Determination of a nutrient budget for the Basin was unachievable because inlet and outlet nutrient concentrations were insufficiently different to override experimental variation. Implications for management of heat inputs to coastal ecosystems include avoidance of areas with high nutrient content, rich organic sediment, or poor flushing. (author)

Tidal pumping drives nutrient and dissolved organic matter dynamics in a Gulf of Mexico subterranean estuary

Science.gov (United States)

Santos, Isaac R.; Burnett, William C.; Dittmar, Thorsten; Suryaputra, I. G. N. A.; Chanton, Jeffrey

2009-03-01

We hypothesize that nutrient cycling in a Gulf of Mexico subterranean estuary (STE) is fueled by oxygen and labile organic matter supplied by tidal pumping of seawater into the coastal aquifer. We estimate nutrient production rates using the standard estuarine model and a non-steady-state box model, separate nutrient fluxes associated with fresh and saline submarine groundwater discharge (SGD), and estimate offshore fluxes from radium isotope distributions. The results indicate a large variability in nutrient concentrations over tidal and seasonal time scales. At high tide, nutrient concentrations in shallow beach groundwater were low as a result of dilution caused by seawater recirculation. During ebb tide, the concentrations increased until they reached a maximum just before the next high tide. The dominant form of nitrogen was dissolved organic nitrogen (DON) in freshwater, nitrate in brackish waters, and ammonium in saline waters. Dissolved organic carbon (DOC) production was two-fold higher in the summer than in the winter, while nitrate and DON production were one order of magnitude higher. Oxic remineralization and denitrification most likely explain these patterns. Even though fresh SGD accounted for only ˜5% of total volumetric additions, it was an important pathway of nutrients as a result of biogeochemical inputs in the mixing zone. Fresh SGD transported ˜25% of DOC and ˜50% of total dissolved nitrogen inputs into the coastal ocean, with the remainder associated with a one-dimensional vertical seawater exchange process. While SGD volumetric inputs are similar seasonally, changes in the biogeochemical conditions of this coastal plain STE led to higher summertime SGD nutrient fluxes (40% higher for DOC and 60% higher for nitrogen in the summer compared to the winter). We suggest that coastal primary production and nutrient dynamics in the STE are linked.

The European Nutrient Database (ENDB) for nutritional epidemiology

DEFF Research Database (Denmark)

Charrondiere, U.R.; Vignat, J.; Møller, Anni Rosendal

2002-01-01

a standardized and critically assessed nutrient database for the 10 countries involved in the European Prospective Investigation into Cancer and Nutrition (EPIC): Denmark, France, Germany, Greece, Great Britain, Italy, The Netherlands, Norway, Spain and Sweden. It will be compiled using the general concept......Food composition databases (FCDB), as well as standardized calculation procedures are required for international studies on nutrition and disease to calculate nutrient intakes across countries. Comparisons of national FCDBs have shown that major improvements are needed in standardization...... for a standardized FCDB, food classification and description, and calculation procedures developed for EPIC. National compilers will provide and document a subset of their nutrient data and some will evaluate them. Updated 'Food Table Input' (FTI) software will be used to evaluate and compile the data. The European...

Wildfire Effects on In-stream Nutrient Processing and Hydrologic Transport

Science.gov (United States)

Rhea, A.; Covino, T. P.; Rhoades, C.; Fegel, T.

2017-12-01

In many forests throughout the Western U.S., drought, climate change, and growing fuel loads are contributing to increased fire frequency and severity. Wildfires can influence watershed nutrient retention as they fundamentally alter the biological composition and physical structure in upland landscapes, riparian corridors, and stream channels. While numerous studies have documented substantial short-term increases in stream nutrient concentrations and export (particularly reactive nitrogen, N) following forest fires, the long-term implications for watershed nutrient cycling remain unclear. For example, recent work indicates that nitrate concentrations and export can remain elevated for a decade or more following wildfire, yet the controls on these processes are unknown. In this research, we use empirical observations from nutrient tracer injections, nutrient diffusing substrates, and continuous water quality monitoring to isolate biological and physical controls on nutrient export across a burn-severity gradient. Tracer results demonstrate substantial stream-groundwater exchange, but little biological nutrient uptake in burned streams. This in part explains patterns of elevated nutrient export. Paired nutrient diffusing substrate experiments allow us to further investigate shifts in N, phosphorus, and carbon limitation that may suppress post-fire stream nutrient uptake. By isolating the mechanisms that reduce the capacity of fire-affected streams to retain and transform nutrient inputs, we can better predict dynamics in post-fire water quality and help prioritize upland and riparian restoration.

Aeolian dust nutrient contributions increase with substrate age in semi-arid ecosystems

Science.gov (United States)

Coble, A. A.; Hart, S. C.; Ketterer, M. E.; Newman, G. S.

2013-12-01

Rock-derived nutrients supplied by mineral weathering become depleted over time, and without an additional nutrient source the ecosystem may eventually regress or reach a terminal steady state. Previous studies have demonstrated that aeolian dust act as parent materials of soils and important nutrients to plants in arid regions, but the relative importance of these exogenous nutrients to the function of dry ecosystems during soil development is uncertain. Here, using strontium isotopes as a tracer and a well-constrained, three million year old substrate age gradient, we show that aeolian-derived nutrients become increasingly important to plant-available soil pools and tree (Pinus edulis) growth during the latter stages of soil development in a semi-arid climate. Furthermore, the depth of nutrient uptake increased on older substrates, suggesting that trees in arid regions acquire nutrients from greater depths as ecosystem development progresses presumably in response to nutrient depletion in the more weathered surface soils. Our results contribute to the unification of biogeochemical theory by demonstrating the similarity in roles of atmospheric nutrient inputs during ecosystem development across contrasting climates.

Long-term atmospheric nutrient inputs to the Eastern Mediterranean: sources, solubility and comparison with riverine inputs

Science.gov (United States)

Koçak, M.; Kubilay, N.; Tuǧrul, S.; Mihalopoulos, N.

2010-07-01

Aerosol and rain samples were collected at a rural site located on the coastline of the Eastern Mediterranean, Erdemli, Turkey between January 1999 and December 2007. Riverine sampling was carried out at five Rivers (Ceyhan, Seyhan, Göksu, Berdan and Lamas) draining into the Northeastern Levantine Basin (NLB) between March 2002 and July 2007. Samples were analyzed for macronutrients of phosphate, silicate, nitrate and ammonium (PO43-, Sidiss, NO3- and NH4+). Phosphate and silicate in aerosol and rainwater showed higher and larger variation during the transitional period (March-May, September) when air flows predominantly originate from North Africa and Middle East/Arabian Peninsula. Deficiency of alkaline material were found to be the main reason of the acidic rain events whilst high pH values (>7) were associated with high Sidiss concentrations due to sporadic dust events. In general, lowest nitrate and ammonium concentrations in aerosol and rainwater were associated with air flow from the Mediterranean Sea. Unlike NO3- and NH4+ (Dissolved Inorganic Nitrogen, DIN), there were statistical differences for PO43- and Sidiss solubilities in sea-water and pure-water. Solubilities of PO43- and Sidiss were found to be related with air mass back trajectories and pH. Comparison of atmospheric with riverine fluxes demonstrated that DIN and PO43- fluxes to NLB were dominated by atmosphere (~90% and ~60% respectively) whereas the input of Si was mainly derived from riverine runoff (~90%). N/P ratios (atmosphere ~233; riverine ~28) revealed that NLB receives excessive amounts of DIN and this unbalanced P and N inputs may provoke even more phosphorus deficiency. Molar Si/N ratios (atmosphere + riverine) suggested Si limitation which might cause a switch from diatom dominated phytoplankton communities to non-siliceous populations in NLB.

Patchiness in a minimal nutrient – phytoplankton model

Indian Academy of Sciences (India)

The mean-field model without the diffusion and advection terms shows both bistability and limit-cycle oscillations as a few parameters such as the input rate of nutrients and the maximum feeding rate of zooplankton are changed. If the parameter values are chosen from the limit-cycle oscillation region, the corresponding ...

Atmospheric Inputs of Nitrogen, Carbon, and Phosphorus across an Urban Area: Unaccounted Fluxes and Canopy Influences

Science.gov (United States)

Decina, Stephen M.; Templer, Pamela H.; Hutyra, Lucy R.

2018-02-01

Rates of atmospheric deposition are declining across the United States, yet urban areas remain hotspots of atmospheric deposition. While past studies show elevated rates of inorganic nitrogen (N) deposition in cities, less is known about atmospheric inputs of organic N, organic carbon (C), and organic and inorganic phosphorus (P), all of which can affect ecosystem processes, water quality, and air quality. Further, the effect of the tree canopy on amounts and forms of nutrients reaching urban ground surfaces is not well-characterized. We measured growing season rates of total N, organic C, and total P in bulk atmospheric inputs, throughfall, and soil solution around the greater Boston area. We found that organic N constitutes a third of total N inputs, organic C inputs are comparable to rural inputs, and inorganic P inputs are 1.2 times higher than those in sewage effluent. Atmospheric inputs are enhanced two-to-eight times in late spring and are elevated beneath tree canopies, suggesting that trees augment atmospheric inputs to ground surfaces. Additionally, throughfall inputs may directly enter runoff when trees extend above impervious surfaces, as is the case with 26.1% of Boston's tree canopy. Our results indicate that the urban atmosphere is a significant source of elemental inputs that may impact urban ecosystems and efforts to improve water quality, particularly in terms of P. Further, as cities create policies encouraging tree planting to provide ecosystem services, locating trees above permeable surfaces to reduce runoff nutrient loads may be essential to managing urban biogeochemical cycling and water quality.

Persistence and extinction of a stochastic single-species population model in a polluted environment with impulsive toxicant input

Directory of Open Access Journals (Sweden)

Meng Liu

2013-10-01

Full Text Available A stochastic single-species population system in a polluted environment with impulsive toxicant input is proposed and studied. Sufficient conditions for extinction, non-persistence in the mean, strong persistence in the mean and stochastic permanence of the population are established. The threshold between strong persistence in the mean and extinction is obtained. Some simulation figures are introduced to illustrate the main results.

Microbial dynamics and enzyme activities in tropical Andosols depending on land use and nutrient inputs

Science.gov (United States)

Mganga, Kevin; Razavi, Bahar; Kuzyakov, Yakov

2015-04-01

Microbial decomposition of soil organic matter is mediated by enzymes and is a key source of terrestrial CO2 emissions. Microbial and enzyme activities are necessary to understand soil biochemical functioning and identify changes in soil quality. However, little is known about land use and nutrients availability effects on enzyme activities and microbial processes, especially in tropical soils of Africa. This study was conducted to examine how microbial and enzyme activities differ between different land uses and nutrient availability. As Andosols of Mt. Kilimanjaro are limited by nutrient concentrations, we hypothesize that N and P additions will stimulate enzyme activity. N and P were added to soil samples (0-20 cm) representing common land use types in East Africa: (1) savannah, (2) maize fields, (3) lower montane forest, (4) coffee plantation, (5) grasslands and (6) traditional Chagga homegardens. Total CO2 efflux from soil, microbial biomass and activities of β-glucosidase, cellobiohydrolase, chitinase and phosphatase involved in C, N and P cycling, respectively was monitored for 60 days. Total CO2 production, microbial biomass and enzyme activities varied in the order forest soils > grassland soils > arable soils. Increased β-glucosidase and cellobiohydrolase activities after N addition of grassland soils suggest that microorganisms increased N uptake and utilization to produce C-acquiring enzymes. Low N concentration in all soils inhibited chitinase activity. Depending on land use, N and P addition had an inhibitory or neutral effect on phosphatase activity. We attribute this to the high P retention of Andosols and low impact of N and P on the labile P fractions. Enhanced CO2 production after P addition suggests that increased P availability could stimulate soil organic matter biodegradation in Andosols. In conclusion, land use and nutrients influenced soil enzyme activities and microbial dynamics and demonstrated the decline in soil quality after landuse

Are large macroalgal blooms necessarily bad? Nutrient impacts on seagrass in upwelling-influenced estuaries.

Science.gov (United States)

Hessing-Lewis, Margot L; Hacker, Sally D; Menge, Bruce A; McConville, Sea-oh; Henderson, Jeremy

2015-07-01

Knowledge of nutrient pathways and their resulting ecological interactions can alleviate numerous environmental problems associated with nutrient increases in both natural and managed systems. Although not unique, coastal systems are particularly prone to complex ecological interactions resulting from nutrient inputs from both the land and sea. Nutrient inputs to coastal systems often spur ulvoid macroalgal blooms, with negative consequences for seagrasses, primarily through shading, as well as through changes in local biogeochemistry. We conducted complementary field and mesocosm experiments in an upwelling-influenced estuary, where marine-derived nutrients dominate, to understand the direct and indirect effects of nutrients on the macroalgal-eelgrass (Zostera marina L.) interaction. In the field experiment, we found weak evidence that nutrients and/or macroalgal treatments had a negative effect on eelgrass. However, in the mesocosm experiment, we found that a combination of nutrient and macroalgal treatments led to strongly negative eelgrass responses, primarily via indirect effects associated with macroalgal additions. Together, increased total light attenuation and decreased sediment oxygen levels were associated with larger effects on eelgrass than shading alone, which was evaluated using mimic algae treatments that did not alter sediment redox potential. Nutrient addition in the mesocosms directly affected seagrass density; biomass, and morphology, but not as strongly as macroalgae. We hypothesize that the contrary results from these parallel experiments are a consequence of differences in the hydrodynamics between field and mesocosm settings. We suggest that the high rates of water movement and tidal submersion of our intertidal field experiments alleviated the light reduction and negative biogeochemical changes in the sediment associated with macroalgal canopies, as well as the nutrient effects observed in the mesocosm experiments. Furthermore, adaptation

Numerical Modeling of the Effects of Nutrient-rich Coastal-water Input on the Phytoplankton in the Gulf of California

Science.gov (United States)

Bermudez, A.; Rivas, D.

2015-12-01

Phytoplankton bloom dynamics depends on the interactions of favorable physical, chemical, and biotic conditions, particularly on the available nutrients that enhance phytoplankton growth, like nitrogen. Costal and estuarine environments are heavily influenced by exogenous sources of nitrogen; the anthropogenic inputs include urban and rural wastewater coming from agricultural activities (i.e., fertilizers and animal waste). In response, new production is often enhanced, leading eutrophication and phytoplankton blooms, including harmful taxa. These events have become more frequent, and with it the interest to evaluate their effects on marine ecosystems and the impact on human health. In the Gulf of California the harmful algal blooms (HABs) had affected aquaculture, fisheries, and even tourism, thereby it is important to generate information about biological and physical factors that can influence their appearance. A numerical model is a tool that may bring key information about the origin and distribution of phytoplankton blooms. Herein the analysis is based on a three-dimensional, hydrodynamical numerical model, coupled to a Nitrogen-Phytoplankton-Zooplankton-Detritus (NPZD) model. Several numerical simulations using different forcing and scenarios are carried out in order to evaluate the processes that influence the phytoplankton growth. These numerical results are compared to available observations. Thus, the main environmental factors triggering the generation of HABs can be identified.

Anthropogenic nutrient sources rival natural sources on small scales in the coastal waters of the Southern California Bight

KAUST Repository

Howard, Meredith D. A.; Sutula, Martha; Caron, David A.; Chao, Yi; Farrara, John D.; Frenzel, Hartmut; Jones, Burton; Robertson, George; McLaughlin, Karen; Sengupta, Ashmita

2014-01-01

Anthropogenic nutrients have been shown to provide significant sources of nitrogen (N) that have been linked to increased primary production and harmful algal blooms worldwide. There is a general perception that in upwelling regions, the flux of anthropogenic nutrient inputs is small relative to upwelling flux, and therefore anthropogenic inputs have relatively little effect on the productivity of coastal waters. To test the hypothesis that natural sources (e.g., upwelling) greatly exceed anthropogenic nutrient sources to the Southern California Bight (SCB), this study compared the source contributions of N from four major nutrient sources: (1) upwelling, (2) treated wastewater effluent discharged to ocean outfalls, (3) riverine runoff, and (4) atmospheric deposition. This comparison was made using large regional data sets combined with modeling on both regional and local scales. At the regional bight-wide spatial scale, upwelling was the largest source of N by an order of magnitude to effluent and two orders of magnitude to riverine runoff. However, at smaller spatial scales, more relevant to algal bloom development, natural and anthropogenic contributions were equivalent. In particular, wastewater effluent and upwelling contributed the same quantity of N in several subregions of the SCB. These findings contradict the currently held perception that in upwelling-dominated regions anthropogenic nutrient inputs are negligible, and suggest that anthropogenic nutrients, mainly wastewater effluent, can provide a significant source of nitrogen for nearshore productivity in Southern California coastal waters.

Anthropogenic nutrient sources rival natural sources on small scales in the coastal waters of the Southern California Bight

KAUST Repository

Howard, Meredith D. A.

2014-01-26

Anthropogenic nutrients have been shown to provide significant sources of nitrogen (N) that have been linked to increased primary production and harmful algal blooms worldwide. There is a general perception that in upwelling regions, the flux of anthropogenic nutrient inputs is small relative to upwelling flux, and therefore anthropogenic inputs have relatively little effect on the productivity of coastal waters. To test the hypothesis that natural sources (e.g., upwelling) greatly exceed anthropogenic nutrient sources to the Southern California Bight (SCB), this study compared the source contributions of N from four major nutrient sources: (1) upwelling, (2) treated wastewater effluent discharged to ocean outfalls, (3) riverine runoff, and (4) atmospheric deposition. This comparison was made using large regional data sets combined with modeling on both regional and local scales. At the regional bight-wide spatial scale, upwelling was the largest source of N by an order of magnitude to effluent and two orders of magnitude to riverine runoff. However, at smaller spatial scales, more relevant to algal bloom development, natural and anthropogenic contributions were equivalent. In particular, wastewater effluent and upwelling contributed the same quantity of N in several subregions of the SCB. These findings contradict the currently held perception that in upwelling-dominated regions anthropogenic nutrient inputs are negligible, and suggest that anthropogenic nutrients, mainly wastewater effluent, can provide a significant source of nitrogen for nearshore productivity in Southern California coastal waters.

Impact of Temperature and Nutrients on Carbon: Nutrient Tissue Stoichiometry of Submerged Aquatic Plants: An Experiment and Meta-Analysis

Directory of Open Access Journals (Sweden)

Mandy Velthuis

2017-05-01

Full Text Available Human activity is currently changing our environment rapidly, with predicted temperature increases of 1–5°C over the coming century and increased nitrogen and phosphorus inputs in aquatic ecosystems. In the shallow parts of these ecosystems, submerged aquatic plants enhance water clarity by resource competition with phytoplankton, provide habitat, and serve as a food source for other organisms. The carbon:nutrient stoichiometry of submerged aquatic plants can be affected by changes in both temperature and nutrient availability. We hypothesized that elevated temperature leads to higher carbon:nutrient ratios through enhanced nutrient-use efficiency, while nutrient addition leads to lower carbon:nutrient ratios by the luxurious uptake of nutrients. We addressed these hypotheses with an experimental and a meta-analytical approach. We performed a full-factorial microcosm experiment with the freshwater plant Elodea nuttallii grown at 10, 15, 20, and 25°C on sediment consisting of pond soil/sand mixtures with 100, 50, 25, and 12.5% pond soil. To address the effect of climatic warming and nutrient addition on the carbon:nutrient stoichiometry of submerged freshwater and marine plants we performed a meta-analysis on experimental studies that elevated temperature and/or added nutrients (nitrogen and phosphorus. In the microcosm experiment, C:N ratios of Elodea nuttallii decreased with increasing temperature, and this effect was most pronounced at intermediate nutrient availability. Furthermore, higher nutrient availability led to decreased aboveground C:P ratios. In the meta-analysis, nutrient addition led to a 25, 22, and 16% reduction in aboveground C:N and C:P ratios and belowground C:N ratios, accompanied with increased N content. No consistent effect of elevated temperature on plant stoichiometry could be observed, as very few studies were found on this topic and contrasting results were reported. We conclude that while nutrient addition

Gene-gene, gene-environment, gene-nutrient interactions and single nucleotide polymorphisms of inflammatory cytokines.

Science.gov (United States)

Nadeem, Amina; Mumtaz, Sadaf; Naveed, Abdul Khaliq; Aslam, Muhammad; Siddiqui, Arif; Lodhi, Ghulam Mustafa; Ahmad, Tausif

2015-05-15

Inflammation plays a significant role in the etiology of type 2 diabetes mellitus (T2DM). The rise in the pro-inflammatory cytokines is the essential step in glucotoxicity and lipotoxicity induced mitochondrial injury, oxidative stress and beta cell apoptosis in T2DM. Among the recognized markers are interleukin (IL)-6, IL-1, IL-10, IL-18, tissue necrosis factor-alpha (TNF-α), C-reactive protein, resistin, adiponectin, tissue plasminogen activator, fibrinogen and heptoglobins. Diabetes mellitus has firm genetic and very strong environmental influence; exhibiting a polygenic mode of inheritance. Many single nucleotide polymorphisms (SNPs) in various genes including those of pro and anti-inflammatory cytokines have been reported as a risk for T2DM. Not all the SNPs have been confirmed by unifying results in different studies and wide variations have been reported in various ethnic groups. The inter-ethnic variations can be explained by the fact that gene expression may be regulated by gene-gene, gene-environment and gene-nutrient interactions. This review highlights the impact of these interactions on determining the role of single nucleotide polymorphism of IL-6, TNF-α, resistin and adiponectin in pathogenesis of T2DM.

Effect of combined water and nutrient management on runoff and sorghum yield in semi-arid Burkina Faso

NARCIS (Netherlands)

Zougmoré, R.; Mando, A.; Ringersma, J.; Stroosnijder, L.

2003-01-01

In the semiarid regions of sub-Saharan Africa, fertilizer recovery and nutrient release from organic sources are often moisture limited. Moreover, in these regions runoff brings about large nutrient losses from fertilizer or organic inputs. This study was conducted in the north sudanian climate zone

Identification of biomechanical nonlinearity in whole-body vibration using a reverse path multi-input-single-output method

Science.gov (United States)

Huang, Ya; Ferguson, Neil S.

2018-04-01

The study implements a classic signal analysis technique, typically applied to structural dynamics, to examine the nonlinear characteristics seen in the apparent mass of a recumbent person during whole-body horizontal random vibration. The nonlinearity in the present context refers to the amount of 'output' that is not correlated or coherent to the 'input', usually indicated by values of the coherence function that are less than unity. The analysis is based on the longitudinal horizontal inline and vertical cross-axis apparent mass of twelve human subjects exposed to 0.25-20 Hz random acceleration vibration at 0.125 and 1.0 ms-2 r.m.s. The conditioned reverse path frequency response functions (FRF) reveal that the uncorrelated 'linear' relationship between physical input (acceleration) and outputs (inline and cross-axis forces) has much greater variation around the primary resonance frequency between 0.5 and 5 Hz. By reversing the input and outputs of the physical system, it is possible to assemble additional mathematical inputs from the physical output forces and mathematical constructs (e.g. square root of inline force). Depending on the specific construct, this can improve the summed multiple coherence at frequencies where the response magnitude is low. In the present case this is between 6 and 20 Hz. The statistical measures of the response force time histories of each of the twelve subjects indicate that there are potential anatomical 'end-stops' for the sprung mass in the inline axis. No previous study has applied this reverse path multi-input-single-output approach to human vibration kinematic and kinetic data before. The implementation demonstrated in the present study will allow new and existing data to be examined using this different analytical tool.

Incorporating hydrologic variability into nutrient spiraling

Science.gov (United States)

Doyle, Martin W.

2005-09-01

Nutrient spiraling describes the path of a nutrient molecule within a stream ecosystem, combining the biochemical cycling processes with the downstream driving force of stream discharge. To date, nutrient spiraling approaches have been hampered by their inability to deal with fluctuating flows, as most studies have characterized nutrient retention within only a small range of discharges near base flow. Here hydrologic variability is incorporated into nutrient spiraling theory by drawing on the fluvial geomorphic concept of effective discharge. The effective discharge for nutrient retention is proposed to be that discharge which, over long periods of time, is responsible for the greatest portion of nutrient retention. A developed analytical model predicts that the effective discharge for nutrient retention will equal the modal discharge for small streams or those with little discharge variability. As modal discharge increases or discharge variability increases, the effective discharge becomes increasingly less than the modal discharge. In addition to the effective discharge, a new metric is proposed, the functionally equivalent discharge, which is the single discharge that will reproduce the magnitude of nutrient retention generated by the full hydrologic frequency distribution when all discharge takes place at that rate. The functionally equivalent discharge was found to be the same as the modal discharge at low hydrologic variability, but increasingly different from the modal discharge at large hydrologic variability. The functionally equivalent discharge provides a simple quantitative means of incorporating hydrologic variability into long-term nutrient budgets.

Issues in ecology: Nutrient pollution of coastal rivers, bays, and seas

Science.gov (United States)

Howarth, Robert W.; Anderson, D. B.; Cloern, James E.; Elfring, Chris; Hopkinson, Charles S.; Lapointe, Brian; Maloney, Thomas J.; Marcus, Nancy; McGlathery, Karen; Sharpley, A.N.; Walker, D.

2000-01-01

Over the past 40 years, antipollution laws have greatly reduced discharges of toxic substances into our coastal waters. This effort, however, has focused largely on point-source pollution of industrial and municipal effluent. No comparable effort has been made to restrict the input of nitrogen (N) from municipal effluent, nor to control the flows of N and phosphorus (P) that enter waterways from dispersed or nonpoint sources such as agricultural and urban runoff or as airborne pollutants. As a result, inputs of nonpoint pollutants, particularly N, have increased dramatically. Nonpoint pollution from N and P now represents the largest pollution problem facing the vital coastal waters of the United States. Nutrient pollution is the common thread that links an array of problems along the nation’s coastline, including eutrophication, harmful algal blooms, ”dead zones,” fish kills, some shellfish poisonings, loss of seagrass and kelp beds, some coral reef destruction, and even some marine mammal and seabird deaths. More than 60 percent of our coastal rivers and bays in every coastal state of the continental United States are moderately to severely degraded by nutrient pollution. This degradation is particularly severe in the mid Atlantic states, in the southeast, and in the Gulf of Mexico. A recent report from the National Research Council entitled “Clean Coastal Waters: Understanding and Reduc- ing the Effects of Nutrient Pollution” concludes that: Nutrient over-enrichment of coastal ecosystems generally triggers ecological changes that decrease the biologi- cal diversity of bays and estuaries. While moderate N enrichment of some coastal waters may increase fish production, over-enrichment generally degrades the marine food web that supports commercially valuable fish. The marked increase in nutrient pollution of coastal waters has been accompanied by an increase in harmful algal blooms, and in at least some cases, pollution has triggered these blooms. High

Low transient storage and uptake efficiencies in seven agricultural streams: implications for nutrient demand.

Science.gov (United States)

Sheibley, Richard W; Duff, John H; Tesoriero, Anthony J

2014-11-01

We used mass load budgets, transient storage modeling, and nutrient spiraling metrics to characterize nitrate (NO), ammonium (NH), and inorganic phosphorus (SRP) demand in seven agricultural streams across the United States and to identify in-stream services that may control these conditions. Retention of one or all nutrients was observed in all but one stream, but demand for all nutrients was low relative to the mass in transport. Transient storage metrics (/, , , and ) correlated with NO retention but not NH or SRP retention, suggesting in-stream services associated with transient storage and stream water residence time could influence reach-scale NO demand. However, because the fraction of median reach-scale travel time due to transient storage () was ≤1.2% across the sites, only a relatively small demand for NO could be generated by transient storage. In contrast, net uptake of nutrients from the water column calculated from nutrient spiraling metrics were not significant at any site because uptake lengths calculated from background nutrient concentrations were statistically insignificant and therefore much longer than the study reaches. These results suggest that low transient storage coupled with high surface water NO inputs have resulted in uptake efficiencies that are not sufficient to offset groundwater inputs of N. Nutrient retention has been linked to physical and hydrogeologic elements that drive flow through transient storage areas where residence time and biotic contact are maximized; however, our findings indicate that similar mechanisms are unable to generate a significant nutrient demand in these streams relative to the loads. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Phosphorus and nitrogen trajectories in the Mediterranean Sea (1950-2030): Diagnosing basin-wide anthropogenic nutrient enrichment

Science.gov (United States)

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

2018-03-01

Human activities have significantly modified the inputs of land-derived phosphorus (P) and nitrogen (N) to the Mediterranean Sea (MS). Here, we reconstruct the external inputs of reactive P and N to the Western Mediterranean Sea (WMS) and Eastern Mediterranean Sea (EMS) over the period 1950-2030. We estimate that during this period the land derived P and N loads increased by factors of 3 and 2 to the WMS and EMS, respectively, with reactive P inputs peaking in the 1980s but reactive N inputs increasing continuously from 1950 to 2030. The temporal variations in reactive P and N inputs are imposed in a coupled P and N mass balance model of the MS to simulate the accompanying changes in water column nutrient distributions and primary production with time. The key question we address is whether these changes are large enough to be distinguishable from variations caused by confounding factors, specifically the relatively large inter-annual variability in thermohaline circulation (THC) of the MS. Our analysis indicates that for the intermediate and deep water masses of the MS the magnitudes of changes in reactive P concentrations due to changes in anthropogenic inputs are relatively small and likely difficult to diagnose because of the noise created by the natural circulation variability. Anthropogenic N enrichment should be more readily detectable in time series concentration data for dissolved organic N (DON) after the 1970s, and for nitrate (NO3) after the 1990s. The DON concentrations in the EMS are predicted to exhibit the largest anthropogenic enrichment signature. Temporal variations in annual primary production over the 1950-2030 period are dominated by variations in deep-water formation rates, followed by changes in riverine P inputs for the WMS and atmospheric P deposition for the EMS. Overall, our analysis indicates that the detection of basin-wide anthropogenic nutrient concentration trends in the MS is rendered difficult due to: (1) the Atlantic Ocean

A method to synchronize signals from multiple patient monitoring devices through a single input channel for inclusion in list-mode acquisitions

International Nuclear Information System (INIS)

O’Connor, J. Michael; Pretorius, P. Hendrik; Johnson, Karen; King, Michael A.

2013-01-01

Purpose: This technical note documents a method that the authors developed for combining a signal to synchronize a patient-monitoring device with a second physiological signal for inclusion into list-mode acquisition. Our specific application requires synchronizing an external patient motion-tracking system with a medical imaging system by multiplexing the tracking input with the ECG input. The authors believe that their methodology can be adapted for use in a variety of medical imaging modalities including single photon emission computed tomography (SPECT) and positron emission tomography (PET). Methods: The authors insert a unique pulse sequence into a single physiological input channel. This sequence is then recorded in the list-mode acquisition along with the R-wave pulse used for ECG gating. The specific form of our pulse sequence allows for recognition of the time point being synchronized even when portions of the pulse sequence are lost due to collisions with R-wave pulses. This was achieved by altering our software used in binning the list-mode data to recognize even a portion of our pulse sequence. Limitations on heart rates at which our pulse sequence could be reliably detected were investigated by simulating the mixing of the two signals as a function of heart rate and time point during the cardiac cycle at which our pulse sequence is mixed with the cardiac signal. Results: The authors have successfully achieved accurate temporal synchronization of our motion-tracking system with acquisition of SPECT projections used in 17 recent clinical research cases. In our simulation analysis the authors determined that synchronization to enable compensation for body and respiratory motion could be achieved for heart rates up to 125 beats-per-minute (bpm). Conclusions: Synchronization of list-mode acquisition with external patient monitoring devices such as those employed in motion-tracking can reliably be achieved using a simple method that can be implemented using

A method to synchronize signals from multiple patient monitoring devices through a single input channel for inclusion in list-mode acquisitions

Energy Technology Data Exchange (ETDEWEB)

O’Connor, J. Michael; Pretorius, P. Hendrik; Johnson, Karen; King, Michael A., E-mail: Michael.King@umassmed.edu [Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655 (United States)

2013-12-15

Purpose: This technical note documents a method that the authors developed for combining a signal to synchronize a patient-monitoring device with a second physiological signal for inclusion into list-mode acquisition. Our specific application requires synchronizing an external patient motion-tracking system with a medical imaging system by multiplexing the tracking input with the ECG input. The authors believe that their methodology can be adapted for use in a variety of medical imaging modalities including single photon emission computed tomography (SPECT) and positron emission tomography (PET). Methods: The authors insert a unique pulse sequence into a single physiological input channel. This sequence is then recorded in the list-mode acquisition along with the R-wave pulse used for ECG gating. The specific form of our pulse sequence allows for recognition of the time point being synchronized even when portions of the pulse sequence are lost due to collisions with R-wave pulses. This was achieved by altering our software used in binning the list-mode data to recognize even a portion of our pulse sequence. Limitations on heart rates at which our pulse sequence could be reliably detected were investigated by simulating the mixing of the two signals as a function of heart rate and time point during the cardiac cycle at which our pulse sequence is mixed with the cardiac signal. Results: The authors have successfully achieved accurate temporal synchronization of our motion-tracking system with acquisition of SPECT projections used in 17 recent clinical research cases. In our simulation analysis the authors determined that synchronization to enable compensation for body and respiratory motion could be achieved for heart rates up to 125 beats-per-minute (bpm). Conclusions: Synchronization of list-mode acquisition with external patient monitoring devices such as those employed in motion-tracking can reliably be achieved using a simple method that can be implemented using

Discrete Input Signaling for MISO Visible Light Communication Channels

KAUST Repository

Arfaoui, Mohamed Amine

2017-05-12

In this paper, we study the achievable secrecy rate of visible light communication (VLC) links for discrete input distributions. We consider single user single eavesdropper multiple-input single-output (MISO) links. In addition, both beamforming and robust beamforming are considered. In the former case, the location of the eavesdropper is assumed to be known, whereas in the latter case, the location of the eavesdropper is unknown. We compare the obtained results with those achieved by some continuous distributions including the truncated generalized normal (TGN) distribution and the uniform distribution. We numerically show that the secrecy rate achieved by the discrete input distribution with a finite support is significantly improved as compared to those achieved by the TGN and the uniform distributions.

Nutrient budgets for large Chinese estuaries

Directory of Open Access Journals (Sweden)

S. M. Liu

2009-10-01

Full Text Available Chinese rivers deliver about 5–10% of global freshwater input and 15–20% of the global continental sediment to the world ocean. We report the riverine fluxes and concentrations of major nutrients (nitrogen, phosphorus, and silicon in the rivers of the contiguous landmass of China and Korea in the northeast Asia. The rivers are generally enriched with dissolved inorganic nitrogen (DIN and depleted in dissolved inorganic phosphate (PO₄³⁻ with very high DIN: PO₄³⁻ concentration ratios. DIN, phosphorus, and silicon levels and loads in rivers are mainly affected by agriculture activities and urbanization, anthropogenic activities and adsorption on particulates, and rock types, climate and physical denudation intensity, respectively. Nutrient transports by rivers in the summer are 3–4 times higher than those in the winter with the exception of NH₄⁺. The flux of NH₄⁺ is rather constant throughout the year due to the anthropogenic sources such as the sewer discharge. As nutrient composition has changed in the rivers, ecosystems in estuaries and coastal sea have also changed in recent decades. Among the changes, a shift of limiting nutrients from phosphorus to nitrogen for phytoplankton production with urbanization is noticeable and in some areas silicon becomes the limiting nutrient for diatom productivity. A simple steady-state mass-balance box model was employed to assess nutrient budgets in the estuaries. The major Chinese estuaries export <15% of nitrogen, <6% of phosphorus required for phytoplankton production and ~4% of silicon required for diatom growth in the Chinese Seas (Bohai, Yellow Sea, East China Sea, South China Sea. This suggests that land-derived nutrients are largely confined to the immediate estuaries, and ecosystem in the coastal sea beyond the estuaries is mainly supported by other nutrient sources such as regeneration, open ocean and

Lateral diffusion of nutrients by mammalian herbivores in terrestrial ecosystems.

Directory of Open Access Journals (Sweden)

Adam Wolf

Full Text Available Animals translocate nutrients by consuming nutrients at one point and excreting them or dying at another location. Such lateral fluxes may be an important mechanism of nutrient supply in many ecosystems, but lack quantification and a systematic theoretical framework for their evaluation. This paper presents a mathematical framework for quantifying such fluxes in the context of mammalian herbivores. We develop an expression for lateral diffusion of a nutrient, where the diffusivity is a biologically determined parameter depending on the characteristics of mammals occupying the domain, including size-dependent phenomena such as day range, metabolic demand, food passage time, and population size. Three findings stand out: (a Scaling law-derived estimates of diffusion parameters are comparable to estimates calculated from estimates of each coefficient gathered from primary literature. (b The diffusion term due to transport of nutrients in dung is orders of magnitude large than the coefficient representing nutrients in bodymass. (c The scaling coefficients show that large herbivores make a disproportionate contribution to lateral nutrient transfer. We apply the diffusion equation to a case study of Kruger National Park to estimate the conditions under which mammal-driven nutrient transport is comparable in magnitude to other (abiotic nutrient fluxes (inputs and losses. Finally, a global analysis of mammalian herbivore transport is presented, using a comprehensive database of contemporary animal distributions. We show that continents vary greatly in terms of the importance of animal-driven nutrient fluxes, and also that perturbations to nutrient cycles are potentially quite large if threatened large herbivores are driven to extinction.

Response of phytoplankton to nutrient enrichment with high growth rates in a tropical monsoonal estuary - Zuari estuary, India

Digital Repository Service at National Institute of Oceanography (India)

Mochemadkar, S.; Gauns, M.; Pratihary, A.K.; Thorat, B.R.; Roy, R.; Pai, I.K.; Naqvi, S.W.A.

nitzschioides exhibited the ability to withstand hypoxic condition. [Keywords: Zuari estuary, Premonsoon, Nutrient uptake, Phytoplankton, Hypoxic] Introduction Phytoplanktons are responsible for nearly half of global primary production1. Diatoms... and fresh water inputs. Light and nutrients are the primary factors regulating phytoplankton growth4,5 followed by temperature and salinity6 . Major (macro) nutrients essential for plant growth are nitrogen, phosphorous and silicon7. Phytoplankton...

Single-phase multi-dimensional thermohydraulics direct numerical simulation code DINUS-3. Input data description

Energy Technology Data Exchange (ETDEWEB)

Muramatsu, Toshiharu [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

1998-08-01

This report explains the numerical methods and the set-up method of input data for a single-phase multi-dimensional thermohydraulics direct numerical simulation code DINUS-3 (Direct Numerical Simulation using a 3rd-order upwind scheme). The code was developed to simulate non-stationary temperature fluctuation phenomena related to thermal striping phenomena, developed at Power Reactor and Nuclear Fuel Development Corporation (PNC). The DINUS-3 code was characterized by the use of a third-order upwind scheme for convection terms in instantaneous Navier-Stokes and energy equations, and an adaptive control system based on the Fuzzy theory to control time step sizes. Author expect this report is very useful to utilize the DINUS-3 code for the evaluation of various non-stationary thermohydraulic phenomena in reactor applications. (author)

Nuclear techniques in integrated plant nutrient, water and soil management. Proceedings

Energy Technology Data Exchange (ETDEWEB)

NONE

2002-04-01

The need to produce sufficient food of acceptable quality in the context of an ever-expanding human population has been recognized as a priority by several international conventions and agreements. Intensification, rather than expansion of agriculture into new areas, will be required if the goal of food security is to become a reality. Problems related to the sustainable production of food, fuel and fibre, both in low input and in high input agricultural systems, are now widely recognized. The overexploitation of the natural resource base has led to serious declines in soil fertility through loss of organic matter, nutrient mining, and soil erosion. The overuse of external inputs of water and manufactured fertilizers has resulted in salinization and pollution of ground and surface waters. Nuclear science has a crucial role to play in supporting research and development of sustainable farming systems. An FAO/IAEA International Symposium on Nuclear Techniques in Integrated Plant Nutrient, Water and Soil Management, held in Vienna from 16 to 20 October 2000, was attended by 117 participants representing forty-three countries and five organizations. The purpose was to provide an international forum for a comprehensive review of the state of the art and recent advances made in this specific field, as well as a basis for delineating further research and development needs. The participation of soil, crop and environmental scientists, as well as isotope specialists, ensured an exchange of information and views on recent advances in interdisciplinary and multidisciplinary approaches to addressing problems in sustainable land management. The symposium was organized around seven themes, each represented by a technical session introduced by a keynote speaker: Evaluation and management of natural and manufactured nutrient sources; Soil organic matter dynamics and nutrient cycling; Soil water management and conservation; Plant tolerance to environmental stress; Environmental and

Nuclear techniques in integrated plant nutrient, water and soil management. Proceedings

International Nuclear Information System (INIS)

2002-01-01

The need to produce sufficient food of acceptable quality in the context of an ever-expanding human population has been recognized as a priority by several international conventions and agreements. Intensification, rather than expansion of agriculture into new areas, will be required if the goal of food security is to become a reality. Problems related to the sustainable production of food, fuel and fibre, both in low input and in high input agricultural systems, are now widely recognized. The overexploitation of the natural resource base has led to serious declines in soil fertility through loss of organic matter, nutrient mining, and soil erosion. The overuse of external inputs of water and manufactured fertilizers has resulted in salinization and pollution of ground and surface waters. Nuclear science has a crucial role to play in supporting research and development of sustainable farming systems. An FAO/IAEA International Symposium on Nuclear Techniques in Integrated Plant Nutrient, Water and Soil Management, held in Vienna from 16 to 20 October 2000, was attended by 117 participants representing forty-three countries and five organizations. The purpose was to provide an international forum for a comprehensive review of the state of the art and recent advances made in this specific field, as well as a basis for delineating further research and development needs. The participation of soil, crop and environmental scientists, as well as isotope specialists, ensured an exchange of information and views on recent advances in interdisciplinary and multidisciplinary approaches to addressing problems in sustainable land management. The symposium was organized around seven themes, each represented by a technical session introduced by a keynote speaker: Evaluation and management of natural and manufactured nutrient sources; Soil organic matter dynamics and nutrient cycling; Soil water management and conservation; Plant tolerance to environmental stress; Environmental and

Nutrients in estuaries - An overview and the potential impacts of climate change

Energy Technology Data Exchange (ETDEWEB)

Statham, Peter J., E-mail: pjs@noc.soton.ac.uk

2012-09-15

The fate and cycling of macronutrients introduced into estuaries depend upon a range of interlinked processes. Hydrodynamics and morphology in combination with freshwater inflow control the freshwater flushing time, and the timescale for biogeochemical processes to operate that include microbial activity, particle-dissolved phase interactions, and benthic exchanges. In some systems atmospheric inputs and exchanges with coastal waters can also be important. Climate change will affect nutrient inputs and behaviour through modifications to temperature, wind patterns, the hydrological cycle, and sea level rise. Resulting impacts include: 1) inundation of freshwater systems 2) changes in stratification, flushing times and phytoplankton productivity 3) increased coastal storm activity 4) changes in species and ecosystem function. A combination of continuing high inputs of nutrients through human activity and climate change is anticipated to lead to enhanced eutrophication in the future. The most obvious impacts of increasing global temperature will be in sub-arctic systems where permafrost zones will be reduced in combination with enhanced inputs from glacial systems. Improved process understanding in several key areas including cycling of organic N and P, benthic exchanges, resuspension, impact of bio-irrigation, particle interactions, submarine groundwater discharges, and rates and magnitude of bacterially-driven recycling processes, is needed. Development of high frequency in situ nutrient analysis systems will provide data to improve predictive models that need to incorporate a wider variety of key factors, although the complexity of estuarine systems makes such modelling a challenge. However, overall a more holistic approach is needed to effectively understand, predict and manage the impact of macronutrients on estuaries. -- Highlights: Black-Right-Pointing-Pointer Estuarine macronutrient behaviour defined by both physical and biogeochemical processes. Black

Surprise! Infants Consider Possible Bases of Generalization for a Single Input Example

Science.gov (United States)

Gerken, LouAnn; Dawson, Colin; Chatila, Razanne; Tenenbaum, Josh

2015-01-01

Infants have been shown to generalize from a small number of input examples. However, existing studies allow two possible means of generalization. One is via a process of noting similarities shared by several examples. Alternatively, generalization may reflect an implicit desire to explain the input. The latter view suggests that generalization…

Persistence and extinction of a single-species population system in a polluted environment with random perturbations and impulsive toxicant input

International Nuclear Information System (INIS)

Liu Meng; Wang Ke

2012-01-01

Highlights: ► Random population model with pulse toxicant input in polluted environments. ► Threshold between persistence and extinction is obtained. ► Different random noises have different effects on the persistence of the population. ► Impulsive period plays a key role in determining persistence of the population. ► Simulation figures support the analytical findings. - Abstract: Taking both white noises and colored noises into account, a stochastic single-species model with Markov switching and impulsive toxicant input in a polluted environment is proposed and investigated. Sufficient conditions for extinction, non-persistence in the mean, weak persistence and stochastic permanence are established. The threshold between weak persistence and extinction is obtained. Some simulation figures are introduced to illustrate the main results.

Nutrient availability at Mer Bleue bog measured by PRSTM probes

Science.gov (United States)

Wang, M.; Moore, T. R.; Talbot, J.

2015-12-01

Bogs, covering ~0.7 million km2 in Canada, store a large amount of C and N. As nutrient deficient ecosystems, it's critical to examine the nutrient availabilities and seasonal dynamics. We used Plant Root Simulators (PRSTM) at Mer Bleue bog to provide some baseline data on nutrient availability and its variability. In particular, we focused on ammonium, nitrate, phosphate, calcium, magnesium and potassium, iron, sulphate and aluminum. We placed PRS probes at a depth of 5 - 15 cm in pristine plots and plots with long term N, P and K fertilization for 4 weeks and determined the availability of these nutrients, from spring through to fall. Probes were also placed beneath the water table in hummock and hollow microtopography and along a transect including part of the bog which had been drained through the creation of a ditch 80 years ago. The result showed that there was limited available ammonium, nitrate and phosphate in the bog, the seasonal variation of nutrient availabilities probably due to mineralization, an increase in the availability of some nutrients between different water table depths or as a result of drainage, and the relative availability of nutrients compared to the input from fertilization. We suggest that PRS probes could be a useful tool to examine nutrient availability and dynamics in wetlands, with careful consideration of installing condition, for example, proper exposure period, depth relative to water table etc.

The role of catchment vegetation in reducing atmospheric inputs of pollutant aerosols in Ganga river.

Science.gov (United States)

Shubhashish, Kumar; Pandey, Richa; Pandey, Jitendra

2012-08-01

The role of woody perennials in the Ganga river basin in modifying the run-off quality as influenced by atmospheric deposition of pollutant aerosols was investigated. The concentration of seven nutrients and eight metals were measured in atmospheric deposits as well as in run-off water under the influence of five woody perennials. Nutrient retention was recorded maximum for Bougainvillea spectabilis ranged from 4.30 % to 33.70 %. Metal retention was recorded highest for Ficus benghalensis ranged from 5.15 % to 36.98 %. Although some species showed nutrient enrichment, all the species considered in the study invariably contribute to reduce nutrients and metal concentration in run-off water. Reduction in run off was recorded maximum for B. spectabilis (nutrient 6.48 %-40.66 %; metal 7.86 %-22.85 %) and minimum for Ficus religiosa (nutrient 1.68 %-27.19 %; metal 6.55 %-31.55 %). The study forms the first report on the use of woody perennials in reducing input of atmospheric pollutants to Ganga river and has relevance in formulating strategies for river basin management.

Whole dairy matrix or single nutrients in assessment of health effects: current evidence and knowledge gaps

NARCIS (Netherlands)

Thorning, Tanja Kongerslev; Bertram, Hanne Christine; Bonjour, Jean-Philippe; Groot, De Lisette; Dupont, Didier; Feeney, Emma; Ipsen, Richard; Lecerf, Jean Michel; Mackie, Alan; Mckinley, Michelle C.; Michalski, Marie-Caroline; Rémond, Didier; Risérus, Ulf; Soedamah-Muthu, Sabita; Tholstrup, Tine; Weaver, Connie; Astrup, Arne; Givens, Ian

2017-01-01

Foods consist of a large number of different nutrients that are contained in a complex structure. The nature of the food structure and the nutrients therein (i.e., the food matrix) will determine the nutrient digestion and absorption, thereby altering the overall nutritional properties of the food.

N and P as ultimate and proximate limiting nutrients in the northern Gulf of Mexico: implications for hypoxia reduction strategies

Directory of Open Access Journals (Sweden)

K. Fennel

2018-05-01

Full Text Available The occurrence of hypoxia in coastal oceans is a long-standing and growing problem worldwide and is clearly linked to anthropogenic nutrient inputs. While the need for reducing anthropogenic nutrient loads is generally accepted, it is costly and thus requires scientifically sound nutrient-reduction strategies. Issues under debate include the relative importance of nitrogen (N and phosphorus (P as well as the magnitude of the reduction requirements. The largest anthropogenically induced hypoxic area in North American coastal waters (of 15 000 ± 5000 km2 forms every summer in the northern Gulf of Mexico where the Mississippi and Atchafalaya rivers deliver large amounts of freshwater and nutrients to the shelf. A 2001 plan for reducing this hypoxic area by nutrient management in the watershed called for a reduction of N loads. Since then evidence of P limitation during the time of hypoxia formation has arisen, and a dual nutrient-reduction strategy for this system has been endorsed. Here we report the first systematic analysis of the effects of single and dual nutrient load reductions from a spatially explicit physical–biogeochemical model for the northern Gulf of Mexico. The model has been shown previously to skillfully represent the processes important for hypoxic formation. Our analysis of an ensemble of simulations with stepwise reductions in N, P, and N and P loads provides insight into the effects of both nutrients on primary production and hypoxia, and it allows us to estimate what nutrient reductions would be required for single and dual nutrient-reduction strategies to reach the hypoxia target. Our results show that, despite temporary P limitation, N is the ultimate limiting nutrient for primary production in this system. Nevertheless, a reduction in P load would reduce hypoxia because primary production is P limited in the region where density stratification is conducive to hypoxia development, but reductions in N load have

Norway spruce fine root dynamics and carbon input into soil in relation to environmental factors

OpenAIRE

Leppälammi-Kujansuu, Jaana

2014-01-01

Knowledge of the quantity of belowground litter carbon (C) input is scarce but highly valued in C budget calculations. Specifically, the turnover rate of fine roots is considered to be one of the most important parameters in the estimation of changes in soil C stock. In this thesis Norway spruce (Picea abies L. (Karst.)) fine root lifespan and litter production and their responses to nutrient availability and temperature were examined. Aboveground foliage and understory litter C inputs were a...

Nutrient enrichment shifts mangrove height distribution: Implications for coastal woody encroachment.

Science.gov (United States)

Weaver, Carolyn A; Armitage, Anna R

2018-01-01

Global changes, such as increased temperatures and elevated CO2, are driving shifts in plant species distribution and dominance, like woody plant encroachment into grasslands. Local factors within these ecotones can influence the rate of regime shifts. Woody encroachment is occurring worldwide, though there has been limited research within coastal systems, where mangrove (woody shrub/tree) stands are expanding into salt marsh areas. Because coastal systems are exposed to various degrees of nutrient input, we investigated how nutrient enrichment may locally impact mangrove stand expansion and salt marsh displacement over time. We fertilized naturally co-occurring Avicennia germinans (black mangrove) and Spartina alterniflora (smooth cordgrass) stands in Port Aransas, TX, an area experiencing mangrove encroachment within the Northern Gulf of Mexico mangrove-marsh ecotone. After four growing seasons (2010-2013) of continuous fertilization, Avicennia was more positively influenced by nutrient enrichment than Spartina. Most notably, fertilized plots had a higher density of taller (> 0.5 m) mangroves and mangrove maximum height was 46% taller than in control plots. Fertilization may promote an increase in mangrove stand expansion within the mangrove-marsh ecotone by shifting Avicennia height distribution. Avicennia individuals, which reach certain species-specific height thresholds, have reduced negative neighbor effects and have higher resilience to freezing temperatures, which may increase mangrove competitive advantage over marsh grass. Therefore, we propose that nutrient enrichment, which augments mangrove height, could act locally as a positive feedback to mangrove encroachment, by reducing mangrove growth suppression factors, thereby accelerating the rates of increased mangrove coverage and subsequent marsh displacement. Areas within the mangrove-marsh ecotone with high anthropogenic nutrient input may be at increased risk of a regime shift from grass to woody

Nutrient enrichment shifts mangrove height distribution: Implications for coastal woody encroachment

Science.gov (United States)

Armitage, Anna R.

2018-01-01

Global changes, such as increased temperatures and elevated CO2, are driving shifts in plant species distribution and dominance, like woody plant encroachment into grasslands. Local factors within these ecotones can influence the rate of regime shifts. Woody encroachment is occurring worldwide, though there has been limited research within coastal systems, where mangrove (woody shrub/tree) stands are expanding into salt marsh areas. Because coastal systems are exposed to various degrees of nutrient input, we investigated how nutrient enrichment may locally impact mangrove stand expansion and salt marsh displacement over time. We fertilized naturally co-occurring Avicennia germinans (black mangrove) and Spartina alterniflora (smooth cordgrass) stands in Port Aransas, TX, an area experiencing mangrove encroachment within the Northern Gulf of Mexico mangrove-marsh ecotone. After four growing seasons (2010–2013) of continuous fertilization, Avicennia was more positively influenced by nutrient enrichment than Spartina. Most notably, fertilized plots had a higher density of taller (> 0.5 m) mangroves and mangrove maximum height was 46% taller than in control plots. Fertilization may promote an increase in mangrove stand expansion within the mangrove-marsh ecotone by shifting Avicennia height distribution. Avicennia individuals, which reach certain species-specific height thresholds, have reduced negative neighbor effects and have higher resilience to freezing temperatures, which may increase mangrove competitive advantage over marsh grass. Therefore, we propose that nutrient enrichment, which augments mangrove height, could act locally as a positive feedback to mangrove encroachment, by reducing mangrove growth suppression factors, thereby accelerating the rates of increased mangrove coverage and subsequent marsh displacement. Areas within the mangrove-marsh ecotone with high anthropogenic nutrient input may be at increased risk of a regime shift from grass to woody

Nutrient transport within and between habitats through seed dispersal processes by woolly monkeys in north-western Amazonia.

Science.gov (United States)

Stevenson, Pablo R; Guzmán-Caro, Diana C

2010-11-01

The contribution of vertebrate animals to nutrient cycling has proven to be important in various ecosystems. However, the role of large bodied primates in nutrient transport in neotropical forests is not well documented. Here, we assess the role of a population of woolly monkeys (Lagothrix lagothricha lugens) as vectors of nutrient movement through seed dispersal. We estimated total seed biomass transported by the population within and between two habitats (terra firme and flooded forests) at Tinigua Park, Colombia, and quantified potassium (K), phosphorus (P) and nitrogen (N) content in seeds of 20 plant species from both forests. Overall, the population transported an estimated minimum of 11.5 (±1.2 SD) g of potassium, 13.2 (±0.7) g of phosphorus and 34.3 (±0.1) g nitrogen, within 22.4 (±2.0) kg of seeds ha(-1) y(-1). Approximately 84% of all nutrients were deposited in the terra firme forest mostly through recycling processes, and also through translocation from the flooded forest. This type of translocation represents an important and high-quality route of transport since abiotic mechanisms do not usually move nutrients upwards, and since chemical tests show that seeds from flooded forests have comparatively higher nutrient contents. The overall contribution to nutrient movement by the population of woolly monkeys is significant because of the large amount of biomass transported, and the high phosphorus content of seeds. As a result, the phosphorus input generated by these monkeys is of the same order of magnitude as other abiotic mechanisms of nutrient transport such as atmospheric deposition and some weathering processes. Our results suggest that via seed dispersal processes, woolly monkey populations can contribute to nutrient movement in tropical forests, and may act as important nutrient input vectors in terra firme forests. © 2010 Wiley-Liss, Inc.

Identification of genotypic variation for nitrogen response in potato (Solanum tuberosum) under low nitrogen input circumstances

OpenAIRE

Tiemens-Hulscher, M.; Lammerts Van Bueren, E.; Struik, P.C.

2009-01-01

Nitrogen is an essential nutrient for crop growth. The demand for nitrogen in the potato crop is relatively high. However, in organic farming nitrogen input is rather limited, compared with conventional farming. In this research nine potato varieties were tested at three nitrogen levels. Genotypic variation for yield, leaf area index, period of maximum soil cover, sensitivity for N-shortage and nitrogen efficiency under low input circumstances was found. However, in these experiments varietie...

The implications of phasing out conventional nutrient supply in organic agriculture

DEFF Research Database (Denmark)

Oelofse, Myles; Jensen, Lars Stoumann; Magid, Jakob

2013-01-01

Soil fertility management in organic systems, regulated by the organic standards, should seek to build healthy, fertile soils and reduce reliance on external inputs. The use of nutrients from conventional sources, such as animal manures from conventional farms, is currently permitted......, with restrictions, in the organic regulations. However, the reliance of organic agriculture on the conventional system is considered problematic. In light of this, the organic sector in Denmark has recently decided to gradually phase out, and ultimately ban, the use of conventional manures and straws in organic...... agriculture in Denmark. Core focal areas for phasing out conventional nutrients are as follows: (1) amendments to crop selection and rotations, (2) alternative nutrient sources (organic wastes) and (3) increased cooperation between organic livestock and arable farmers. Using Denmark as a case, this article...

Nutrient supply to organic agriculture as governed by EU regulations and standards in six European countries

DEFF Research Database (Denmark)

Løes, Anne Kristin; Bünemann, E.K.; Cooper, J.

2017-01-01

-farm P sources include conventional animal manure, composted or anaerobically digested organic residues, rock phosphate, and some animal residues such as meat and bone meal. The recent proposed revision of EU regulations for organic production (2014) puts less emphasis on closing nutrient cycles...... as means are taken to ensure the quality and safety of these inputs. Awareness of the need to close nutrient cycles may contribute to adapting regulations and private standards to support recycling of nutrients from society to organic agriculture. A better definition of the term “natural substance...

Nutrients in estuaries — An overview and the potential impacts of climate change

International Nuclear Information System (INIS)

Statham, Peter J.

2012-01-01

The fate and cycling of macronutrients introduced into estuaries depend upon a range of interlinked processes. Hydrodynamics and morphology in combination with freshwater inflow control the freshwater flushing time, and the timescale for biogeochemical processes to operate that include microbial activity, particle-dissolved phase interactions, and benthic exchanges. In some systems atmospheric inputs and exchanges with coastal waters can also be important. Climate change will affect nutrient inputs and behaviour through modifications to temperature, wind patterns, the hydrological cycle, and sea level rise. Resulting impacts include: 1) inundation of freshwater systems 2) changes in stratification, flushing times and phytoplankton productivity 3) increased coastal storm activity 4) changes in species and ecosystem function. A combination of continuing high inputs of nutrients through human activity and climate change is anticipated to lead to enhanced eutrophication in the future. The most obvious impacts of increasing global temperature will be in sub-arctic systems where permafrost zones will be reduced in combination with enhanced inputs from glacial systems. Improved process understanding in several key areas including cycling of organic N and P, benthic exchanges, resuspension, impact of bio-irrigation, particle interactions, submarine groundwater discharges, and rates and magnitude of bacterially-driven recycling processes, is needed. Development of high frequency in situ nutrient analysis systems will provide data to improve predictive models that need to incorporate a wider variety of key factors, although the complexity of estuarine systems makes such modelling a challenge. However, overall a more holistic approach is needed to effectively understand, predict and manage the impact of macronutrients on estuaries. -- Highlights: ► Estuarine macronutrient behaviour defined by both physical and biogeochemical processes. ► Climate change impacts: sea level

Temporal responses of coastal hypoxia to nutrient loading and physical controls

Directory of Open Access Journals (Sweden)

W. M. Kemp

2009-12-01

Full Text Available The incidence and intensity of hypoxic waters in coastal aquatic ecosystems has been expanding in recent decades coincident with eutrophication of the coastal zone. Worldwide, there is strong interest in reducing the size and duration of hypoxia in coastal waters, because hypoxia causes negative effects for many organisms and ecosystem processes. Although strategies to reduce hypoxia by decreasing nutrient loading are predicated on the assumption that this action would reverse eutrophication, recent analyses of historical data from European and North American coastal systems suggest little evidence for simple linear response trajectories. We review published parallel time-series data on hypoxia and loading rates for inorganic nutrients and labile organic matter to analyze trajectories of oxygen (O₂ response to nutrient loading. We also assess existing knowledge of physical and ecological factors regulating O₂ in coastal marine waters to facilitate analysis of hypoxia responses to reductions in nutrient (and/or organic matter inputs. Of the 24 systems identified where concurrent time series of loading and O₂ were available, half displayed relatively clear and direct recoveries following remediation. We explored in detail 5 well-studied systems that have exhibited complex, non-linear responses to variations in loading, including apparent "regime shifts". A summary of these analyses suggests that O₂ conditions improved rapidly and linearly in systems where remediation focused on organic inputs from sewage treatment plants, which were the primary drivers of hypoxia. In larger more open systems where diffuse nutrient loads are more important in fueling O₂ depletion and where climatic influences are pronounced, responses to remediation tended to follow non-linear trends that may include hysteresis and time-lags. Improved understanding of hypoxia remediation requires that future studies use

Phytoplankton and nutrient dynamics in Winyah Bay, SC.

Science.gov (United States)

Boneillo, G. E.; Brooks, S. S.; Brown, S. L.; Woodford, K. M.; Wright, C. R.

2016-02-01

Winyah Bay is a coastal plain estuary located in South Carolina that has been classified for a moderate risk of Eutrophication by NOAA. Winyah Bay receives freshwater input from four rivers, the Waccamaw, Sampit, Black, and Pee Dee Rivers. The Waccamaw, Sampit and Black River are blackwater systems that discharge elevated amounts of colored dissolved organic matter. During the summer and fall of 2015, bioassay experiments were performed to simultaneously examine both light and nutrient (nitrogen & phosphate) limitation throughout Winyah Bay. Sampling stations near the mouth of the Waccamaw and Sampit Rivers showed that phytoplankton were light limited in the late summer instead of nutrient limited. These stations were located in the industrialized area of the bay and typically had the highest nutrient concentrations and highest turbidity, with Secchi depths typically less than 0.5 meters. Results indicated that phytoplankton may be nitrogen limited near the mouth of Winyah Bay, where nutrient concentrations and turbidity were observed to be lower than locations further upstream. There was also an observed dissolved oxygen and pH gradient during the summer of 2015. Dissolved oxygen levels less than 4.0 mg/L were routinely observed near the industrialized head of the estuary and corresponded with lower pH values.

Analyses of single nucleotide polymorphisms in selected nutrient-sensitive genes in weight-regain prevention: the DIOGENES study.

Science.gov (United States)

Larsen, Lesli H; Angquist, Lars; Vimaleswaran, Karani S; Hager, Jörg; Viguerie, Nathalie; Loos, Ruth J F; Handjieva-Darlenska, Teodora; Jebb, Susan A; Kunesova, Marie; Larsen, Thomas M; Martinez, J Alfredo; Papadaki, Angeliki; Pfeiffer, Andreas F H; van Baak, Marleen A; Sørensen, Thorkild Ia; Holst, Claus; Langin, Dominique; Astrup, Arne; Saris, Wim H M

2012-05-01

Differences in the interindividual response to dietary intervention could be modified by genetic variation in nutrient-sensitive genes. This study examined single nucleotide polymorphisms (SNPs) in presumed nutrient-sensitive candidate genes for obesity and obesity-related diseases for main and dietary interaction effects on weight, waist circumference, and fat mass regain over 6 mo. In total, 742 participants who had lost ≥ 8% of their initial body weight were randomly assigned to follow 1 of 5 different ad libitum diets with different glycemic indexes and contents of dietary protein. The SNP main and SNP-diet interaction effects were analyzed by using linear regression models, corrected for multiple testing by using Bonferroni correction and evaluated by using quantile-quantile (Q-Q) plots. After correction for multiple testing, none of the SNPs were significantly associated with weight, waist circumference, or fat mass regain. Q-Q plots showed that ALOX5AP rs4769873 showed a higher observed than predicted P value for the association with less waist circumference regain over 6 mo (-3.1 cm/allele; 95% CI: -4.6, -1.6; P/Bonferroni-corrected P = 0.000039/0.076), independently of diet. Additional associations were identified by using Q-Q plots for SNPs in ALOX5AP, TNF, and KCNJ11 for main effects; in LPL and TUB for glycemic index interaction effects on waist circumference regain; in GHRL, CCK, MLXIPL, and LEPR on weight; in PPARC1A, PCK2, ALOX5AP, PYY, and ADRB3 on waist circumference; and in PPARD, FABP1, PLAUR, and LPIN1 on fat mass regain for dietary protein interaction. The observed effects of SNP-diet interactions on weight, waist, and fat mass regain suggest that genetic variation in nutrient-sensitive genes can modify the response to diet. This trial was registered at clinicaltrials.gov as NCT00390637.

A CMOS/SOI Single-input PWM Discriminator for Low-voltage Body-implanted Applications

Directory of Open Access Journals (Sweden)

Jader A. De Lima

2002-01-01

Full Text Available A CMOS/SOI circuit to decode Pulse-Width Modulation (PWM signals is presented as part of a body-implanted neurostimulator for visual prosthesis. Since encoded data is the sole input to the circuit, the decoding technique is based on a novel double-integration concept and does not require low-pass filtering. Non-overlapping control phases are internally derived from the incoming pulses and a fast-settling comparator ensures good discrimination accuracy in the megahertz range. The circuit was integrated on a 2 μm single-metal thin-film CMOS/SOI fabrication process and has an effective area of 2 mm2. Measured resolution of encoding parameter α is better than 10% at 6 MHz and VDD = 3.3 V. Idle-mode consumption is 340 μW. Pulses of frequencies up to15 MHz and α =10% can be discriminated for 2.3 V ≤ VDD ≤ 3.3 V. Such an excellent immunity to VDD deviations meets a design specification with respect to inherent coupling losses on transmitting data and power by means of a transcutaneous link.

New topology of multiple-input single-output PV system for DC load applications

Directory of Open Access Journals (Sweden)

Mohsen M. ELhagry

2016-12-01

Full Text Available Improving PV system structure and maximizing the output power of a PV system has drawn many researchers attention nowadays. A proposed multi-input single-output PV system is proposed in this paper. The system consists of multiple PV modules; each module feeds a DC–DC converter. The outputs of the converters are tied together to form a DC voltage source. In order to minimize the output ripples of the converters, the control signal of each converter is time shifted from each other by a certain time interval depending on the number of converters used in the topology. In this study a battery is used as the main load, the load current used as the control variable. A fuzzy logic controller designed to modulate the operating point of the system to get the maximum power. The results show that the proposed system has very good response for various operating conditions of the PV system. In addition the output filter is minimized with excellent quality of the DC output voltage.

Unprecedented carbon accumulation in mined soils: the synergistic effect of resource input and plant species invasion.

Science.gov (United States)

Silva, Lucas C R; Corrêa, Rodrigo S; Doane, Timothy A; Pereira, Engil I P; Horwath, William R

2013-09-01

Opencast mining causes severe impacts on natural environments, often resulting in permanent damage to soils and vegetation. In the present study we use a 14-year restoration chronosequence to investigate how resource input and spontaneous plant colonization promote the revegetation and reconstruction of mined soils in central Brazil. Using a multi-proxy approach, combining vegetation surveys with the analysis of plant and soil isotopic abundances (delta13C and delta15N) and chemical and physical fractionation of organic matter in soil profiles, we show that: (1) after several decades without vegetation cover, the input of nutrient-rich biosolids into exposed regoliths prompted the establishment of a diverse plant community (> 30 species); (2) the synergistic effect of resource input and plant colonization yielded unprecedented increases in soil carbon, accumulating as chemically stable compounds in occluded physical fractions and reaching much higher levels than observed in undisturbed ecosystems; and (3) invasive grasses progressively excluded native species, limiting nutrient availability, but contributing more than 65% of the total accumulated soil organic carbon. These results show that soil-plant feedbacks regulate the amount of available resources, determining successional trajectories and alternative stable equilibria in degraded areas undergoing restoration. External inputs promote plant colonization, soil formation, and carbon sequestration, at the cost of excluding native species. The introduction of native woody species would suppress invasive grasses and increase nutrient availability, bringing the system closer to its original state. However, it is difficult to predict whether soil carbon levels could be maintained without the exotic grass cover. We discuss theoretical and practical implications of these findings, describing how the combination of resource manipulation and management of invasive species could be used to optimize restoration strategies

Nutrient variations and isotopic evidences of particulate organic matter provenance in fringing reefs, South China

International Nuclear Information System (INIS)

Cao, Di; Cao, Wenzhi; Liang, Ying; Huang, Zheng

2016-01-01

Nutrient over-enrichment is considered to be one of the causes of coral decline. Increase in traditional fishing in the Xuwen National Coral Reefs Reserve tract (XW) and tourism around the Sanya National Coral Reefs Reserve tract (SY) are causing this coral decline. This study reviews the current state of knowledge of the nutrient status of coastal fringing reefs in South China and evaluates the primary sources of nutrients using stable isotope method. Surveys of seawater nutrients showed that the seawater remained clean in both the XW and SY coastal coral reef areas. Based on the isotopic differences between anthropogenic sewage and naturally occurring aquatic nutrients, the isotopic values of particulate organic matter (POM) and the C/N ratios were successfully used to identify the presence of anthropogenic nutrients in aquatic environments. The δ"1"3C, δ"1"5N and C/N compositions of POM from XW and SY (− 21.18 ± 2.11‰, 10.30 ± 5.54‰, and 5.35 ± 0.69 and − 20.80 ± 1.34‰, 7.06 ± 3.95‰, and 5.77 ± 2.15, respectively) showed statistically significant variations with the season. The δ"1"3C and δ"1"5N values of POM suggest marine and terrestrial-derived nutrient sources. Organic carbon is a mixture of marine phytoplankton, marine benthic algae and terrestrial-derived plants. The δ"1"5N values suggest terrestrial-derived sewage and upwelling-dominated nitrogen sources. In the presence of natural upwelling and coastal currents, coastal coral reef areas are more vulnerable to the increasing anthropogenic nutrient inputs. Anthropogenic activities might lead to large increases in the nutrient concentrations and could trigger the shift from coral- to macroalgae-dominated ecosystems, which would ultimately result in the degradation of the coastal coral reef ecosystem. These results provide some understanding of the declining coral reef ecosystem and the importance of conservation areas and coastal coral reef resource management. - Highlights: • The

Nutrient variations and isotopic evidences of particulate organic matter provenance in fringing reefs, South China

Energy Technology Data Exchange (ETDEWEB)

Cao, Di; Cao, Wenzhi, E-mail: wzcao@xmu.edu.cn; Liang, Ying; Huang, Zheng

2016-10-01

Nutrient over-enrichment is considered to be one of the causes of coral decline. Increase in traditional fishing in the Xuwen National Coral Reefs Reserve tract (XW) and tourism around the Sanya National Coral Reefs Reserve tract (SY) are causing this coral decline. This study reviews the current state of knowledge of the nutrient status of coastal fringing reefs in South China and evaluates the primary sources of nutrients using stable isotope method. Surveys of seawater nutrients showed that the seawater remained clean in both the XW and SY coastal coral reef areas. Based on the isotopic differences between anthropogenic sewage and naturally occurring aquatic nutrients, the isotopic values of particulate organic matter (POM) and the C/N ratios were successfully used to identify the presence of anthropogenic nutrients in aquatic environments. The δ{sup 13}C, δ{sup 15}N and C/N compositions of POM from XW and SY (− 21.18 ± 2.11‰, 10.30 ± 5.54‰, and 5.35 ± 0.69 and − 20.80 ± 1.34‰, 7.06 ± 3.95‰, and 5.77 ± 2.15, respectively) showed statistically significant variations with the season. The δ{sup 13}C and δ{sup 15}N values of POM suggest marine and terrestrial-derived nutrient sources. Organic carbon is a mixture of marine phytoplankton, marine benthic algae and terrestrial-derived plants. The δ{sup 15}N values suggest terrestrial-derived sewage and upwelling-dominated nitrogen sources. In the presence of natural upwelling and coastal currents, coastal coral reef areas are more vulnerable to the increasing anthropogenic nutrient inputs. Anthropogenic activities might lead to large increases in the nutrient concentrations and could trigger the shift from coral- to macroalgae-dominated ecosystems, which would ultimately result in the degradation of the coastal coral reef ecosystem. These results provide some understanding of the declining coral reef ecosystem and the importance of conservation areas and coastal coral reef resource management

Effect of enhanced nitrogen input on release of nutrients and nutrient availability in stands of tall fern Athyrium distentifolium

Science.gov (United States)

Tå¯Ma, Ivan; Holuib, Petr; Záhora, Jaroslav; Fiala, Karel

2010-05-01

Improved light conditions, after destruction of tree canopy, soil acidification and increased nitrogen availability, support intensive spreading of acidophilous perennial grasses and stands of tall fern (Athyrium distentifolium) on deforested sites in the Moravian-Silesian Beskydy Mts. (the Czech Republic). The aim of the study was to determine how higher inputs of nitrogen affect the release of nutrients during decomposition processes of fern litter. The experimental site was chosen on a southwest-facing slope of the Kněhyně Mt. (49o31´ N, 18o 32´E, 1170 m a.s.l.) in the Moravian-Silesin Beskydy Mts. in the Czech Republic. The area is characterized by an annual mean air temperature of 5.6 oC and annual precipitation of 1110 mm. A large fern stand was divided in four blocks (5x3 m) and on two of them higher doses of nitrogen were applied (50 kgN/ha in five doses in the course of the growing season). Similarly, mesh-bags with fresh natural litter of fern were used to determine rate of litter decomposition during one year. Samples were inserted in both nitrogen treated and untreated fern stands in autumn 2006 and 2007 collected in autumn 2007 and 2008. On the basis of litter amount estimated at the start and at the end of exposure and of actual content of minerals in original and exposed litter, the release and/or accumulation of minerals during decomposition were calculated. The availability (more or less in the case of ammonia-nitrogen) and movement of percolated nitrogen (mainly in the case of nitrate-nitrogen) was estimated in situ by the trapping of mineral N into the ion exchange resin (IER) inserted into special cover. The decomposition rate of native A. distentifolium litter was approximately the same (29-30 %) at both nitrogen availability, however the element release from decomposed litter was higher for N, P and Ca in both years and for K and Mg in the first year as well. However, decomposition rate of cellulose was two times greater in fern stands

Soil nutrient enhancement by rice husk in smallholder farms of the ...

African Journals Online (AJOL)

Soil fertility management is one of the most cherished natural resource that requires being safeguard at all cost. An adequate and better solution to combat soil constraint arising from nutrient depletion has been developed; a low external input technology, amending soils with an organic base fertilizer (rice husk) as it is high ...

Atmospheric nutrient inputs to the northern levantine basin from a long-term observation: sources and comparison with riverine inputs

Science.gov (United States)

Koçak, M.; Kubilay, N.; Tuğrul, S.; Mihalopoulos, N.

2010-12-01

Aerosol and rainwater samples have been collected at a rural site located on the coastline of the Eastern Mediterranean, Erdemli, Turkey between January 1999 and December 2007. Riverine sampling was carried out at five Rivers (Ceyhan, Seyhan, Göksu, Berdan and Lamas) draining into the Northeastern Levantine Basin (NLB) between March 2002 and July 2007. Samples have been analyzed for macronutrients of phosphate, silicate, nitrate and ammonium (PO43-, Sidiss, NO3- and NH4+). Phosphate and silicate in aerosol and rainwater showed higher and larger variations during the transitional period when air flows predominantly originate from North Africa and Middle East/Arabian Peninsula. Deficiency of alkaline material have been found to be the main reason of the acidic rain events whilst high pH values (>7) have been associated with high Sidiss concentrations due to sporadic dust events. In general, lowest nitrate and ammonium concentrations in aerosol and rainwater have been associated with air flow from the Mediterranean Sea. Comparison of atmospheric with riverine fluxes demonstrated that DIN and PO43- fluxes to NLB have been dominated by atmosphere (~90% and ~60% respectively) whereas the input of Si was mainly derived from riverine runoff (~90%). N/P ratios in the atmospheric deposition (233); riverine discharge (28) revealed that NLB receives excessive amounts of DIN and this unbalanced P and N inputs may provoke even more phosphorus deficiency. Observed molar Si/N ratio suggested Si limitation relative to nitrogen might cause a switch from diatom dominated communities to non-siliceous populations particularly at coastal NLB.

Lake nutrient stoichiometry is less predictable than nutrient concentrations at regional and sub-continental scales.

Science.gov (United States)

Collins, Sarah M; Oliver, Samantha K; Lapierre, Jean-Francois; Stanley, Emily H; Jones, John R; Wagner, Tyler; Soranno, Patricia A

2017-07-01

Production in many ecosystems is co-limited by multiple elements. While a known suite of drivers associated with nutrient sources, nutrient transport, and internal processing controls concentrations of phosphorus (P) and nitrogen (N) in lakes, much less is known about whether the drivers of single nutrient concentrations can also explain spatial or temporal variation in lake N:P stoichiometry. Predicting stoichiometry might be more complex than predicting concentrations of individual elements because some drivers have similar relationships with N and P, leading to a weak relationship with their ratio. Further, the dominant controls on elemental concentrations likely vary across regions, resulting in context dependent relationships between drivers, lake nutrients and their ratios. Here, we examine whether known drivers of N and P concentrations can explain variation in N:P stoichiometry, and whether explaining variation in stoichiometry differs across regions. We examined drivers of N:P in ~2,700 lakes at a sub-continental scale and two large regions nested within the sub-continental study area that have contrasting ecological context, including differences in the dominant type of land cover (agriculture vs. forest). At the sub-continental scale, lake nutrient concentrations were correlated with nutrient loading and lake internal processing, but stoichiometry was only weakly correlated to drivers of lake nutrients. At the regional scale, drivers that explained variation in nutrients and stoichiometry differed between regions. In the Midwestern U.S. region, dominated by agricultural land use, lake depth and the percentage of row crop agriculture were strong predictors of stoichiometry because only phosphorus was related to lake depth and only nitrogen was related to the percentage of row crop agriculture. In contrast, all drivers were related to N and P in similar ways in the Northeastern U.S. region, leading to weak relationships between drivers and stoichiometry

Exploring the nutrient inputs and cycles in Tampa Bay and coastal watersheds using MODIS images and data mining

Science.gov (United States)

Chang, Ni-Bin; Xuan, Zhemin

2011-09-01

Excessive nutrients, which may be represented as Total Nitrogen (TN) and Total Phosphorus (TP) levels, in natural water systems have proven to cause high levels of algae production. The process of phytoplankton growth which consumes the excess TN and TP in a water body can also be related to the changing water quality levels, such as Dissolved Oxygen (DO), chlorophyll-a, and turbidity, associated with their changes in absorbance of natural radiation. This paper explores spatiotemporal nutrient patterns in Tampa Bay, Florida with the aid of Moderate Resolution Imaging Spectroradiometer or MODIS images and Genetic Programming (GP) models that are deigned to link those relevant water quality parameters in aquatic environments.

The imprint of crop choice on global nutrient needs

International Nuclear Information System (INIS)

Jobbágy, Esteban G; Sala, Osvaldo E

2014-01-01

Solutions to meet growing food requirements in a world of limited suitable land and degrading environment focus mainly on increasing crop yields, particularly in poorly performing regions, and reducing animal product consumption. Increasing yields could alleviate land requirements, but imposing higher soil nutrient withdrawals and in most cases larger fertilizer inputs. Lowering animal product consumption favors a more efficient use of land as well as soil and fertilizer nutrients; yet actual saving may largely depend on which crops and how much fertilizer are used to feed livestock versus people. We show, with a global analysis, how the choice of cultivated plant species used to feed people and livestock influences global food production as well as soil nutrient withdrawals and fertilizer additions. The 3 to 15-fold differences in soil nutrient withdrawals per unit of energy or protein produced that we report across major crops explain how composition shifts over the last 20 years have reduced N, maintained P and increased K harvest withdrawals from soils while contributing to increasing dietary energy, protein and, particularly, vegetable fat outputs. Being highly variable across crops, global fertilization rates do not relate to actual soil nutrient withdrawals, but to monetary values of harvested products. Future changes in crop composition could contribute to achieve more sustainable food systems, optimizing land and fertilizer use. (letter)

Swift recovery of Sphagnum nutrient concentrations after excess supply.

Science.gov (United States)

Limpens, Juul; Heijmans, Monique M P D

2008-08-01

Although numerous studies have addressed the effects of increased N deposition on nutrient-poor environments such as raised bogs, few studies have dealt with to what extent, and on what time-scale, reductions in atmospheric N supply would lead to recovery of the ecosystems in question. Since a considerable part of the negative effects of elevated N deposition on raised bogs can be related to an imbalance in tissue nutrient concentrations of the dominant peat-former Sphagnum, changes in Sphagnum nutrient concentration after excess N supply may be used as an early indicator of ecosystem response. This study focuses on the N and P concentrations of Sphagnum magellanicum and Sphagnum fallax before, during and after a factorial fertilization experiment with N and P in two small peatlands subject to a background bulk deposition of 2 g N m(-2) year(-1). Three years of adding N (4.0 g N m(-2) year(-1)) increased the N concentration, and adding P (0.3 g P m(-2) year(-1)) increased the P concentration in Sphagnum relative to the control treatment at both sites. Fifteen months after the nutrient additions had ceased, N concentrations were similar to the control whereas P concentrations, although strongly reduced, were still slightly elevated. The changes in the N and P concentrations were accompanied by changes in the distribution of nutrients over the capitulum and the stem and were congruent with changes in translocation. Adding N reduced the stem P concentration, whereas adding P reduced the stem N concentration in favor of the capitulum. Sphagnum nutrient concentrations quickly respond to reductions in excess nutrient supply, indicating that a management policy aimed at reducing atmospheric nutrient input to bogs can yield results within a few years.

Hydrologic connectivity to streams increases nitrogen and phosphorus inputs and cycling in soils of created and natural floodplain wetlands

Science.gov (United States)

Wolf, Kristin L.; Noe, Gregory; Ahn, Changwoo

2013-01-01

Greater connectivity to stream surface water may result in greater inputs of allochthonous nutrients that could stimulate internal nitrogen (N) and phosphorus (P) cycling in natural, restored, and created riparian wetlands. This study investigated the effects of hydrologic connectivity to stream water on soil nutrient fluxes in plots (n = 20) located among four created and two natural freshwater wetlands of varying hydrology in the Piedmont physiographic province of Virginia. Surface water was slightly deeper; hydrologic inputs of sediment, sediment-N, and ammonium were greater; and soil net ammonification, N mineralization, and N turnover were greater in plots with stream water classified as their primary water source compared with plots with precipitation or groundwater as their primary water source. Soil water-filled pore space, inputs of nitrate, and soil net nitrification, P mineralization, and denitrification enzyme activity (DEA) were similar among plots. Soil ammonification, N mineralization, and N turnover rates increased with the loading rate of ammonium to the soil surface. Phosphorus mineralization and ammonification also increased with sedimentation and sediment-N loading rate. Nitrification flux and DEA were positively associated in these wetlands. In conclusion, hydrologic connectivity to stream water increased allochthonous inputs that stimulated soil N and P cycling and that likely led to greater retention of sediment and nutrients in created and natural wetlands. Our findings suggest that wetland creation and restoration projects should be designed to allow connectivity with stream water if the goal is to optimize the function of water quality improvement in a watershed.

Salmon-mediated nutrient flux in selected streams of the Columbia River basin, USA

Science.gov (United States)

Kohler, Andre E.; Kusnierz, Paul C.; Copeland, Timothy; Venditti, David A.; Denny, Lytle; Gable, Josh; Lewis, Bert; Kinzer, Ryan; Barnett, Bruce; Wipfli, Mark S.

2013-01-01

Salmon provide an important resource subsidy and linkage between marine and land-based ecosystems. This flow of energy and nutrients is not uni-directional (i.e., upstream only); in addition to passive nutrient export via stream flow, juvenile emigrants actively export nutrients from freshwater environments. In some cases, nutrient export can exceed import. We evaluated nutrient fluxes in streams across central Idaho, USA using Chinook salmon (Oncorhynchus tshawytscha) adult escapement and juvenile production data from 1998 to 2008. We found in the majority of stream-years evaluated, adults imported more nutrients than progeny exported; however, in 3% of the years, juveniles exported more nutrients than their parents imported. On average, juvenile emigrants exported 22 ± 3% of the nitrogen and 30 ± 4% of the phosphorus their parents imported. This relationship was density dependent and nonlinear; during periods of low adult abundance juveniles were larger and exported up to 194% and 268% of parental nitrogen and phosphorus inputs, respectively. We highlight minimum escapement thresholds that appear to 1) maintain consistently positive net nutrient flux and 2) reduce the average proportional rate of export across study streams. Our results suggest a state-shift occurs when adult spawner abundance falls below a threshold to a point where the probability of juvenile nutrient exports exceeding adult imports becomes increasingly likely.

Nutrient-dependent/pheromone-controlled adaptive evolution: a model

Directory of Open Access Journals (Sweden)

James Vaughn Kohl

2013-06-01

Full Text Available Background: The prenatal migration of gonadotropin-releasing hormone (GnRH neurosecretory neurons allows nutrients and human pheromones to alter GnRH pulsatility, which modulates the concurrent maturation of the neuroendocrine, reproductive, and central nervous systems, thus influencing the development of ingestive behavior, reproductive sexual behavior, and other behaviors. Methods: This model details how chemical ecology drives adaptive evolution via: (1 ecological niche construction, (2 social niche construction, (3 neurogenic niche construction, and (4 socio-cognitive niche construction. This model exemplifies the epigenetic effects of olfactory/pheromonal conditioning, which alters genetically predisposed, nutrient-dependent, hormone-driven mammalian behavior and choices for pheromones that control reproduction via their effects on luteinizing hormone (LH and systems biology. Results: Nutrients are metabolized to pheromones that condition behavior in the same way that food odors condition behavior associated with food preferences. The epigenetic effects of olfactory/pheromonal input calibrate and standardize molecular mechanisms for genetically predisposed receptor-mediated changes in intracellular signaling and stochastic gene expression in GnRH neurosecretory neurons of brain tissue. For example, glucose and pheromones alter the hypothalamic secretion of GnRH and LH. A form of GnRH associated with sexual orientation in yeasts links control of the feedback loops and developmental processes required for nutrient acquisition, movement, reproduction, and the diversification of species from microbes to man. Conclusion: An environmental drive evolved from that of nutrient ingestion in unicellular organisms to that of pheromone-controlled socialization in insects. In mammals, food odors and pheromones cause changes in hormones such as LH, which has developmental affects on pheromone-controlled sexual behavior in nutrient-dependent reproductively

Single input state, single–mode fiber–based polarization sensitive optical frequency domain imaging by eigenpolarization referencing

Science.gov (United States)

Lippok, Norman; Villiger, Martin; Jun, Chang–Su; Bouma, Brett E.

2015-01-01

Fiber–based polarization sensitive OFDI is more challenging than free–space implementations. Using multiple input states, fiber–based systems provide sample birefringence information with the benefit of a flexible sample arm but come at the cost of increased system and acquisition complexity, and either reduce acquisition speed or require increased acquisition bandwidth. Here we show that with the calibration of a single polarization state, fiber–based configurations can approach the conceptual simplicity of traditional free–space configurations. We remotely control the polarization state of the light incident at the sample using the eigenpolarization states of a wave plate as a reference, and determine the Jones matrix of the output fiber. We demonstrate this method for polarization sensitive imaging of biological samples. PMID:25927775

Interactive effects of vertical mixing, nutrients and ultraviolet radiation: in situ photosynthetic responses of phytoplankton from high mountain lakes in Southern Europe

Science.gov (United States)

Helbling, E. W.; Carrillo, P.; Medina-Sánchez, J. M.; Durán, C.; Herrera, G.; Villar-Argaiz, M.; Villafañe, V. E.

2013-02-01

Global change, together with human activities, has resulted in increasing amounts of organic material (including nutrients) that water bodies receive. This input further attenuates the penetration of solar radiation, leading to the view that opaque lakes are more "protected" from solar ultraviolet radiation (UVR) than clear ones. Vertical mixing, however, complicates this view as cells are exposed to fluctuating radiation regimes, for which the effects have, in general, been neglected. Furthermore, the combined impacts of mixing, together with those of UVR and nutrient inputs are virtually unknown. In this study, we carried out complex in situ experiments in three high mountain lakes of Spain (Lake Enol in the National Park Picos de Europa, Asturias, and lakes Las Yeguas and La Caldera in the National Park Sierra Nevada, Granada), used as model ecosystems to evaluate the joint impact of these climate change variables. The main goal of this study was to address the question of how short-term pulses of nutrient inputs, together with vertical mixing and increased UVR fluxes modify the photosynthetic responses of phytoplankton. The experimentation consisted in all possible combinations of the following treatments: (a) solar radiation: UVR + PAR (280-700 nm) versus PAR (photosynthetically active radiation) alone (400-700 nm); (b) nutrient addition (phosphorus (P) and nitrogen (N)): ambient versus addition (P to reach to a final concentration of 30 μg P L-1, and N to reach N:P molar ratio of 31); and (c) mixing: mixed (one rotation from surface to 3 m depth (speed of 1 m 4 min-1, total of 10 cycles)) versus static. Our findings suggest that under ambient nutrient conditions there is a synergistic effect between vertical mixing and UVR, increasing phytoplankton photosynthetic inhibition and excretion of organic carbon (EOC) from opaque lakes as compared to algae that received constant mean irradiance within the epilimnion. The opposite occurs in clear lakes where

Interactive effects of vertical mixing, nutrients and ultraviolet radiation: in situ photosynthetic responses of phytoplankton from high mountain lakes in Southern Europe

Directory of Open Access Journals (Sweden)

E. W. Helbling

2013-02-01

Full Text Available Global change, together with human activities, has resulted in increasing amounts of organic material (including nutrients that water bodies receive. This input further attenuates the penetration of solar radiation, leading to the view that opaque lakes are more "protected" from solar ultraviolet radiation (UVR than clear ones. Vertical mixing, however, complicates this view as cells are exposed to fluctuating radiation regimes, for which the effects have, in general, been neglected. Furthermore, the combined impacts of mixing, together with those of UVR and nutrient inputs are virtually unknown. In this study, we carried out complex in situ experiments in three high mountain lakes of Spain (Lake Enol in the National Park Picos de Europa, Asturias, and lakes Las Yeguas and La Caldera in the National Park Sierra Nevada, Granada, used as model ecosystems to evaluate the joint impact of these climate change variables. The main goal of this study was to address the question of how short-term pulses of nutrient inputs, together with vertical mixing and increased UVR fluxes modify the photosynthetic responses of phytoplankton. The experimentation consisted in all possible combinations of the following treatments: (a solar radiation: UVR + PAR (280–700 nm versus PAR (photosynthetically active radiation alone (400–700 nm; (b nutrient addition (phosphorus (P and nitrogen (N: ambient versus addition (P to reach to a final concentration of 30 μg P L⁻¹, and N to reach N:P molar ratio of 31; and (c mixing: mixed (one rotation from surface to 3 m depth (speed of 1 m 4 min⁻¹, total of 10 cycles versus static. Our findings suggest that under ambient nutrient conditions there is a synergistic effect between vertical mixing and UVR, increasing phytoplankton photosynthetic inhibition and excretion of organic carbon (EOC from opaque lakes as compared to algae that received constant mean irradiance within the epilimnion. The

Economic Optimization of Nutrient Application to Coffee in Northern Tanzania Using SAFERNAC

NARCIS (Netherlands)

Maro, G.P.; Janssen, B.H.; Msanya, B.M.; Mrema, J.P.

2014-01-01

The aim of this work, as an extension to SAFERNAC model, was to establish economically optimum combinations of N, P and K application to Arabica coffee in the Northern coffee zone of Tanzania. The study was conducted in Hai and Lushoto districts between 2010 and 2012. Prices of nutrient inputs and

Assessment of nutrient loadings of a large multipurpose prairie reservoir

Science.gov (United States)

Morales-Marín, L. A.; Wheater, H. S.; Lindenschmidt, K. E.

2017-07-01

The relatively low water flow velocities in reservoirs cause them to have high capacities for retaining sediments and pollutants, which can lead to a reduction in downstream nutrient loading. Hence, nutrients can progressively accumulate in reservoirs, resulting in the deterioration of aquatic ecosystems and water quality. Lake Diefenbaker (LD) is a large multipurpose reservoir, located on the South Saskatchewan River (SSR), that serves as a major source of freshwater in Saskatchewan, Canada. Over the past several years, changes in land use (e.g. expansion of urban areas and industrial developments) in the reservoir's catchment have heightened concerns about future water quality in the catchment and in the reservoir. Intensification of agricultural activities has led to an increase in augmented the application of manure and fertilizer for crops and pasture. Although previous research has attempted to quantify nutrient retention in LD, there is a knowledge gap related to the identification of major nutrient sources and quantification of nutrient export from the catchment at different spatial scales. Using the SPAtially Referenced Regression On Watershed (SPARROW) model, this gap has been addressed by assessing water quality regionally, and identifying spatial patterns of factors and processes that affect water quality in the LD catchment. Model results indicate that LD retains about 70% of the inflowing total nitrogen (TN) and 90% of the inflowing total phosphorus (TP) loads, of which fertilizer and manure applied to agricultural fields contribute the greatest proportion. The SPARROW model will be useful as a tool to guide the optimal implementation of nutrient management plans to reduce nutrient inputs to LD.

Identification of genotypic variation for nitrogen response in potato (Solanum tuberosum) under low nitrogen input circumstances

NARCIS (Netherlands)

Tiemens-Hulscher, M.; Lammerts Van Bueren, E.; Struik, P.C.

2009-01-01

Nitrogen is an essential nutrient for crop growth. The demand for nitrogen in the potato crop is relatively high. However, in organic farming nitrogen input is rather limited, compared with conventional farming. In this research nine potato varieties were tested at three nitrogen levels. Genotypic

Evolution of farm management, nitrogen efficiency and economic performance on Dutch dairy farms reducing external inputs

NARCIS (Netherlands)

Groot, J.C.J.; Rossing, W.A.H.; Lantinga, E.A.

2006-01-01

The implementation of the statutory Mineral Accounting System (MINAS) in the Netherlands in the period 1998¿2003 required large reductions in nutrient inputs of dairy farms. Patterns in farm management adjustments throughout 6 years and their effectiveness in terms of nitrogen use efficiency (NUE)

Are seagrass beds indicators of anthropogenic nutrient stress in the rocky intertidal?

International Nuclear Information System (INIS)

Honig, Susanna E.; Mahoney, Brenna; Glanz, Jess S.; Hughes, Brent B.

2017-01-01

It is well established that anthropogenic nutrient inputs harm estuarine seagrasses, but the influence of nutrients in rocky intertidal ecosystems is less clear. In this study, we investigated the effect of anthropogenic nutrient loading on Phyllospadix spp., a rocky intertidal seagrass, at local and regional scales. At sites along California, Washington, and Oregon, we demonstrated a significant, negative correlation of urban development and Phyllospadix bed thickness. These results were echoed locally along an urban gradient on the central California coast, where Phyllospadix shoot δ 15 N was negatively associated with Phyllospadix bed thickness, and experimentally, where nutrient additions in mesocosms reduced Phyllospadix shoot formation and increased epiphytic cover on Phyllospadix shoots. These findings provide evidence that coastal development can threaten rocky intertidal seagrasses through increased epiphytism. Considering that seagrasses provide vital ecosystem services, mitigating eutrophication and other factors associated with development in the rocky intertidal coastal zone should be a management priority. - Highlights: • The effect of nutrient loading on rocky intertidal seagrasses is not well studied. • Regionally, development was negatively associated with Phyllospadix bed thickness. • Locally, shoot δ 15 N was negatively associated with Phyllospadix bed thickness. • Mesocosms with added nutrients had a net loss in shoots and increased epiphytes. • Nutrient loading may have a negative effect on intertidal seagrass bed health.

Nutrient depletion in Bacillus subtilis biofilms triggers matrix production

International Nuclear Information System (INIS)

Zhang, Wenbo; Seminara, Agnese; Suaris, Melanie; Angelini, Thomas E; Brenner, Michael P; Weitz, David A

2014-01-01

Many types of bacteria form colonies that grow into physically robust and strongly adhesive aggregates known as biofilms. A distinguishing characteristic of bacterial biofilms is an extracellular polymeric substance (EPS) matrix that encases the cells and provides physical integrity to the colony. The EPS matrix consists of a large amount of polysaccharide, as well as protein filaments, DNA and degraded cellular materials. The genetic pathways that control the transformation of a colony into a biofilm have been widely studied, and yield a spatiotemporal heterogeneity in EPS production. Spatial gradients in metabolites parallel this heterogeneity in EPS, but nutrient concentration as an underlying physiological initiator of EPS production has not been explored. Here, we study the role of nutrient depletion in EPS production in Bacillus subtilis biofilms. By monitoring simultaneously biofilm size and matrix production, we find that EPS production increases at a critical colony thickness that depends on the initial amount of carbon sources in the medium. Through studies of individual cells in liquid culture we find that EPS production can be triggered at the single-cell level by reducing nutrient concentration. To connect the single-cell assays with conditions in the biofilm, we calculate carbon concentration with a model for the reaction and diffusion of nutrients in the biofilm. This model predicts the relationship between the initial concentration of carbon and the thickness of the colony at the point of internal nutrient deprivation. (paper)

Quantum theory of multiple-input-multiple-output Markovian feedback with diffusive measurements

International Nuclear Information System (INIS)

Chia, A.; Wiseman, H. M.

2011-01-01

Feedback control engineers have been interested in multiple-input-multiple-output (MIMO) extensions of single-input-single-output (SISO) results of various kinds due to its rich mathematical structure and practical applications. An outstanding problem in quantum feedback control is the extension of the SISO theory of Markovian feedback by Wiseman and Milburn [Phys. Rev. Lett. 70, 548 (1993)] to multiple inputs and multiple outputs. Here we generalize the SISO homodyne-mediated feedback theory to allow for multiple inputs, multiple outputs, and arbitrary diffusive quantum measurements. We thus obtain a MIMO framework which resembles the SISO theory and whose additional mathematical structure is highlighted by the extensive use of vector-operator algebra.

Evaluation of nutrient retention in vegetated filter strips using the SWAT model.

Science.gov (United States)

Elçi, Alper

2017-11-01

Nutrient fluxes in stream basins need to be controlled to achieve good water quality status. In stream basins with intensive agricultural activities, nutrients predominantly come from diffuse sources. Therefore, best management practices (BMPs) are increasingly implemented to reduce nutrient input to streams. The objective of this study is to evaluate the impact of vegetated filter strip (VFS) application as an agricultural BMP. For this purpose, SWAT is chosen, a semi-distributed water quality assessment model that works at the watershed scale, and applied on the Nif stream basin, a small-sized basin in Western Turkey. The model is calibrated with an automated procedure against measured monthly discharge data. Nutrient loads for each sub-basin are estimated considering basin-wide data on chemical fertilizer and manure usage, population data for septic tank effluents and information about the land cover. Nutrient loads for 19 sub-basins are predicted on an annual basis. Average total nitrogen and total phosphorus loads are estimated as 47.85 t/yr and 13.36 t/yr for the entire basin. Results show that VFS application in one sub-basin offers limited retention of nutrients and that a selection of 20-m filter width is most effective from a cost-benefit perspective.

Reciprocal effects of litter from exotic and congeneric native plant species via soil nutrients

NARCIS (Netherlands)

Meisner, A.; De Boer, W.; Cornelissen, J.H.C.; Van der Putten, W.H.

2012-01-01

Invasive exotic plant species are often expected to benefit exclusively from legacy effects of their litter inputs on soil processes and nutrient availability. However, there are relatively few experimental tests determining how litter of exotic plants affects their own growth conditions compared to

Human waste: An underestimated source of nutrient pollution in coastal seas of Bangladesh, India and Pakistan.

Science.gov (United States)

Amin, Md Nurul; Kroeze, Carolien; Strokal, Maryna

2017-05-15

Many people practice open defecation in south Asia. As a result, lot of human waste containing nutrients such as nitrogen (N) and phosphorus (P) enter rivers. Rivers transport these nutrients to coastal waters, resulting in marine pollution. This source of nutrient pollution is, however, ignored in many nutrient models. We quantify nutrient export by large rivers to coastal seas of Bangladesh, India and Pakistan, and the associated eutrophication potential in 2000 and 2050. Our new estimates for N and P inputs from human waste are one to two orders of magnitude higher than earlier model calculations. This leads to higher river export of nutrients to coastal seas, increasing the risk of coastal eutrophication potential (ICEP). The newly calculated future ICEP, for instance, Godavori river is 3 times higher than according to earlier studies. Our modeling approach is simple and transparent and can easily be applied to other data-poor basins. Copyright © 2017 Elsevier Ltd. All rights reserved.

On the input distribution and optimal beamforming for the MISO VLC wiretap channel

KAUST Repository

Arfaoui, Mohamed Amine; Rezki, Zouheir; Ghrayeb, Ali; Alouini, Mohamed-Slim

2017-01-01

We investigate in this paper the achievable secrecy rate of the multiple-input single-output (MISO) visible light communication (VLC) Gaussian wiretap channel with single user and single eavesdropper. We consider the cases when the location of eavesdropper is known or unknown to the transmitter. In the former case, we derive the optimal beamforming in closed form, subject to constrained inputs. In the latter case, we apply robust beamforming. Furthermore, we study the achievable secrecy rate when the input follows the truncated generalized normal (TGN) distribution. We present several examples which demonstrate the substantial improvements in the secrecy rates achieved by the proposed techniques.

On the input distribution and optimal beamforming for the MISO VLC wiretap channel

KAUST Repository

Arfaoui, Mohamed Amine

2017-05-12

We investigate in this paper the achievable secrecy rate of the multiple-input single-output (MISO) visible light communication (VLC) Gaussian wiretap channel with single user and single eavesdropper. We consider the cases when the location of eavesdropper is known or unknown to the transmitter. In the former case, we derive the optimal beamforming in closed form, subject to constrained inputs. In the latter case, we apply robust beamforming. Furthermore, we study the achievable secrecy rate when the input follows the truncated generalized normal (TGN) distribution. We present several examples which demonstrate the substantial improvements in the secrecy rates achieved by the proposed techniques.

Atmospheric nutrient inputs to the northern levantine basin from a long-term observation: sources and comparison with riverine inputs

Directory of Open Access Journals (Sweden)

M. Koçak

2010-12-01

Full Text Available Aerosol and rainwater samples have been collected at a rural site located on the coastline of the Eastern Mediterranean, Erdemli, Turkey between January 1999 and December 2007. Riverine sampling was carried out at five Rivers (Ceyhan, Seyhan, Göksu, Berdan and Lamas draining into the Northeastern Levantine Basin (NLB between March 2002 and July 2007. Samples have been analyzed for macronutrients of phosphate, silicate, nitrate and ammonium (PO₄³⁻, Si_diss, NO₃⁻ and NH₄⁺. Phosphate and silicate in aerosol and rainwater showed higher and larger variations during the transitional period when air flows predominantly originate from North Africa and Middle East/Arabian Peninsula. Deficiency of alkaline material have been found to be the main reason of the acidic rain events whilst high pH values (>7 have been associated with high Si_diss concentrations due to sporadic dust events. In general, lowest nitrate and ammonium concentrations in aerosol and rainwater have been associated with air flow from the Mediterranean Sea. Comparison of atmospheric with riverine fluxes demonstrated that DIN and PO₄³⁻ fluxes to NLB have been dominated by atmosphere (~90% and ~60% respectively whereas the input of Si was mainly derived from riverine runoff (~90%. N/P ratios in the atmospheric deposition (233; riverine discharge (28 revealed that NLB receives excessive amounts of DIN and this unbalanced P and N inputs may provoke even more phosphorus deficiency. Observed molar Si/N ratio suggested Si limitation relative to nitrogen might cause a switch from diatom dominated communities to non-siliceous populations particularly at coastal NLB.

Nutrients, Recycling, and Biological Populations in Upwelling Ecosystems

Energy Technology Data Exchange (ETDEWEB)

Whitledge, T. E.

1980-01-01

Nutrient recycling has been studied in the upwelling areas of Baja California, Northwest Africa, and Peru. Regeneration by biological populations in these areas contributes significant quantities of recycled nitrogen which is utilized in productivity processes. Each area has a different combination of organisms which leads to differences in the relative contributions of zooplankton, nekton, or benthos to the nutrient cycles. Comparisons of ammonium regeneration rates of zooplankton and nekton-micronekton populations in the three upwelling areas show that zooplankton recycle relatively less nitrogen in the Baja California and Peru systems than nekton. In the Northwest Africa upwelling region, however, zooplankton, fish, and benthic inputs are all substantial. In recent years the Peruvian upwelling system has been altered with the decline of the anchoveta population and an increase in the importance of zooplankton in nutrient recycling. The distribution of recycled nitrogen (ammonium and urea) in transects across the shelf at 10°S and 15°S indicates that regeneration is relatively more important at 10°S in the region of the wide shelf. In both areas the distribution of ammonium and urea are not entirely coincident thereby indicating differences in their production and/or utilization.

Combined impact of ultraviolet radiation and increased nutrients supply: A test of the potential anthropogenic impacts on the benthic amphipod Amphitoe valida from Patagonian waters (Argentina

Directory of Open Access Journals (Sweden)

Macarena S. Valiñas

2014-08-01

Full Text Available Experiments were conducted during the Austral Summer of 2014 to determine the effects of increased nutrient input and ultraviolet radiation (UVR on the food consumption rate (FCR and food preference in the amphipod Amphitoe valida. We collected specimens from the Patagonian coast (Argentina, from beaches close (Barrancas Blancas; BB and further away (Cangrejales; C from the Chubut River, which constitutes the potential source of eutrophication. Organisms were exposed to different radiation regimes (full radiation vs. PAR only and fed with different macroalgae diets (i.e., from different geographical location and with different quality in terms on nutrient content. Males collected from C showed food compensation, consuming more food under low-nutrient diets, while no compensation was observed in males from BB. Regardless of their origin, UVR decreased the FCR when males where fed on ambient nutrient diets, but not when males fed on high-quality diets indicating that in the former case, individuals were in worse physiological conditions to cope with UVR; food quality, however, significantly counteracted the deleterious effects of UVR on FCR. Females collected from the two beaches showed similar FCR under high-nutrient diet and had no food compensation when fed in low-nutrient diets. Females were more vulnerable to UVR, since their FCR were lower when exposed to UV radiation independent of the diet. Our results show that under anthropogenic eutrophication and high solar UVR levels an increase in the nutrient input could favor only males of A. valida, by reducing the negative effects of UVR on their FCR. Nevertheless, these nutrient inputs might cause additional problems like anoxia, as a result of an unusual macroalgal growth, thus affecting amphipod’s survival.

Estimating the unknown components of nutrient mass balances for forestry plantations in mine rehabilitation, upper Hunter Valley, New South Wales, Australia.

Science.gov (United States)

Mercuri, A M; Duggin, J A; Daniel, H; Lockwood, P V; Grant, C D

2006-04-01

Commercial forestry plantations as a postmining land use in the Upper Hunter Valley of New South Wales, Australia are restricted by both the poor nutrient availability of mining substrates and low regional rainfall. An experiment was conducted to investigate whether municipal waste products and saline groundwater from coal mining operations could improve early tree growth without impacting on the environment through salt accumulation and/or nutrient enrichment and changes in groundwater quality. Potential impacts were investigated by quantifying the nutrient cycling dynamics within the plantation using an input-output mass balance approach for exchangeable calcium (Ca(2+)), exchangeable magnesium (Mg(2+)), exchangeable potassium (K(+)), exchangeable sodium (Na(+)), nitrogen (N), and phosphorus (P). Measured inputs to and outputs from the available nutrient pool in the 0-30 cm of the overburden subsystem were used to estimate the net effect of unmeasured inputs and outputs (termed "residuals"). Residual values in the mass balance of the irrigated treatments demonstrated large leaching losses of exchangeable Ca, Mg, K, and Na. Between 96% and 103% of Na applied in saline mine-water irrigation was leached below the 0-30-cm soil profile zone. The fate of these salts beyond 30 cm is unknown, but results suggest that irrigation with saline mine water had minimal impact on the substrate to 30 cm over the first 2 years since plantation establishment. Accumulations of N and P were detected for the substrate amendments, suggesting that organic amendments (particularly compost) retained the applied nutrients with very little associated losses, particularly through leaching.

Simulation of land use impacts on sediment and nutrient transfer in coastal areas of Western Cape, South Africa

Directory of Open Access Journals (Sweden)

Gebel Micha

2017-01-01

Full Text Available A major challenge for water resource management in Western Cape, South Africa, is the reduction of the growing sediment and nutrient loads in coastal areas, which belong to the areas most affected by land use change. We used the WebGIS based software STOFFBILANZ to simulate runoff, soil loss, sediment, phosphorus, and nitrogen input in the surface water and groundwater of study area (ca. 6,450 km². The simulated runoff shows a large regional variability caused by the heterogeneous distribution of rainfall. For the reference catchment Klein River simulated total daily runoff fit the observed values of the reference year 2012. The calculation of potential input of sediment, phosphorus, and nitrogen into waters is based on aggregated or generalized information on climate data, land use types, crop and fruit types, yields, mineral fertilizers, farm manure, nitrogen fixing by leguminous plants, atmospheric nitrogen deposition, and soil denitrification. Critical source areas for potential sediment input, particulate P input and diffuse N input are mainly agricultural areas. Additionally, point sources of high relevance for N and P are found in urban areas. Based on the potential input of sediment and nutrients the impacts of current land use change on water resources were estimated. We used the web-based information system WebLand for the simulation aiming at the provision of stakeholders with information for decision making in water resource management.

Nutrient disequilibrium in agro-ecosystems: Concepts and case studies

International Nuclear Information System (INIS)

Smaling, Eric

2002-01-01

Full text: Amongst the problems that African agriculture faces, soil fertility decline is mentioned as a major pressure. The declining state (lower soil fertility) has led to different responses by researchers, landusers and policy makers. All responses directly or indirectly boil down to some form of 'Integrated Nutrient Management' (INM), which is defined as the 'judicious' manipulation of nutrient stocks and flows. As INM is complex and multi-faceted, it is difficult to derive simple indicators for policy makers from it. The concept of stocks (state) and flows (pressure), however, links well with economic sciences. A continental study revealed that Africa is losing nutrients at a rather alarming rate, i.e., 22 kg N, 2.5 kg P and 15 kg K per ha per year (Stoorvogel and Smaling, 1990). These values represent the sum of the outputs minus the sum of the inputs mentioned below. IN 1 mineral fertilizer OUT 1 nutrients in harvested parts, milk, meat, etc. IN 2 organic fertilizer OUT 2 nutrients in removed crop residues IN 3 atmospheric deposition OUT 3 leaching IN 4 biological N fixation OUT 4 gaseous losses IN 5 sedimentation OUT 5 runoff and erosion This study however, commissioned by FAO, had to deal with a lot of higher-scale problems, i.e., using FAO's production yearbooks, using the 1:5,000,000 FAO Soil Map of the World, generalisation, simplification, and the use of proxies (transfer functions). It triggered many studies at lower spatial scales (field, farm, village, watershed), in which inputs and outputs are accompanied by internal flows within the system. In other words, INM can be geared towards: adding nutrients to the system; saving nutrient from being lost from the system; recycling so as to maximize nutrient use efficiency. Measurement of nutrient flows is complex: a simple fertilizer trial implies adding nutrients, and harvesting part of the extra nutrients, but what happens to the nutrients that were not taken up by the crop? More spatially complex is

Hydrologic connectivity to streams increases nitrogen and phosphorus inputs and cycling in soils of created and natural floodplain wetlands.

Science.gov (United States)

Wolf, Kristin L; Noe, Gregory B; Ahn, Changwoo

2013-07-01

Greater connectivity to stream surface water may result in greater inputs of allochthonous nutrients that could stimulate internal nitrogen (N) and phosphorus (P) cycling in natural, restored, and created riparian wetlands. This study investigated the effects of hydrologic connectivity to stream water on soil nutrient fluxes in plots ( = 20) located among four created and two natural freshwater wetlands of varying hydrology in the Piedmont physiographic province of Virginia. Surface water was slightly deeper; hydrologic inputs of sediment, sediment-N, and ammonium were greater; and soil net ammonification, N mineralization, and N turnover were greater in plots with stream water classified as their primary water source compared with plots with precipitation or groundwater as their primary water source. Soil water-filled pore space, inputs of nitrate, and soil net nitrification, P mineralization, and denitrification enzyme activity (DEA) were similar among plots. Soil ammonification, N mineralization, and N turnover rates increased with the loading rate of ammonium to the soil surface. Phosphorus mineralization and ammonification also increased with sedimentation and sediment-N loading rate. Nitrification flux and DEA were positively associated in these wetlands. In conclusion, hydrologic connectivity to stream water increased allochthonous inputs that stimulated soil N and P cycling and that likely led to greater retention of sediment and nutrients in created and natural wetlands. Our findings suggest that wetland creation and restoration projects should be designed to allow connectivity with stream water if the goal is to optimize the function of water quality improvement in a watershed. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Transport and Fate of Nutrients Along the U.S. East Coast

Science.gov (United States)

Hofmann, E. E.; Narvaez, D.; Friedrichs, M. A. M.; Najjar, R.; Tian, H.; Hyde, K.; Mannino, A.; Signorini, S. R.; Wilkin, J.; St-Laurent, P.

2017-12-01

As part of a NASA-funded multi-investigator project, a land-estuarine-ocean biogeochemical modeling system was implemented and verified with remote sensing and in situ data to examine processes controlling fluxes on land, their coupling to riverine systems, the delivery of materials to estuaries and the coastal ocean, and marine ecosystem responses to these changing riverine inputs and changing climate forcing. This modeling system is being used to develop nutrient budgets for the U.S. east coast continental shelf and to examine seasonal and interannual variability in nutrient fluxes. An important aspect of these nutrient budgets is the transport and fate of nutrients released along the inner shelf. Results from a five-year simulation (2004 to 2008) that used tracer releases from the main rivers along the Middle Atlantic Bight (MAB) and South Atlantic Bight (SAB) provide insights into transport pathways that connect the inner and outer continental shelf. Tracers released along the inner MAB spread along the shelf with a general southward and offshore transport. Inner shelf inputs from the large estuarine systems are transported to the mid and outer MAB shelf. Tracers that reach the mid to outer shelf can be entrained in the Gulf Stream. Export from the MAB to the SAB occurs during periods of southerly winds. Transport processes along the SAB are similar, but Gulf Stream entrainment is a larger component of tracer transport. Superimposed on the MAB and SAB transport patterns is considerable seasonal and interannual variability. The results from these retrospective simulations improve understanding of the coupling at the land-water interface and shelf-wide transport patterns that advance the ability to predict the effects of localized human impacts and broader-scale climate-related impacts on the U.S. east coast continental shelf system.

Bulk deposition of base cationic nutrients in China's forests: Annual rates and spatial characteristics

Science.gov (United States)

Enzai Du; Wim de Vries; Steven McNulty; Mark E. Fenn

2018-01-01

Base cations, such as potassium (K+), calcium (Ca2+) and magnesium (Mg2+), are essential nutrients for plant growth and their atmospheric inputs can buffer the effect of acid deposition by nitrogen (N) and sulphur (S) compounds. However, the spatial variation in atmospheric deposition of these base...

Multiple stressors in agricultural streams: a mesocosm study of interactions among raised water temperature, sediment addition and nutrient enrichment.

Directory of Open Access Journals (Sweden)

Jeremy J Piggott

Full Text Available Changes to land use affect streams through nutrient enrichment, increased inputs of sediment and, where riparian vegetation has been removed, raised water temperature. We manipulated all three stressors in experimental streamside channels for 30 days and determined the individual and pair-wise combined effects on benthic invertebrate and algal communities and on leaf decay, a measure of ecosystem functioning. We added nutrients (phosphorus+nitrogen; high, intermediate, natural and/or sediment (grain size 0.2 mm; high, intermediate, natural to 18 channels supplied with water from a nearby stream. Temperature was increased by 1.4°C in half the channels, simulating the loss of upstream and adjacent riparian shade. Sediment affected 93% of all biological response variables (either as an individual effect or via an interaction with another stressor generally in a negative manner, while nutrient enrichment affected 59% (mostly positive and raised temperature 59% (mostly positive. More of the algal components of the community responded to stressors acting individually than did invertebrate components, whereas pair-wise stressor interactions were more common in the invertebrate community. Stressors interacted often and in a complex manner, with interactions between sediment and temperature most common. Thus, the negative impact of high sediment on taxon richness of both algae and invertebrates was stronger at raised temperature, further reducing biodiversity. In addition, the decay rate of leaf material (strength loss accelerated with nutrient enrichment at ambient but not at raised temperature. A key implication of our findings for resource managers is that the removal of riparian shading from streams already subjected to high sediment inputs, or land-use changes that increase erosion or nutrient runoff in a landscape without riparian buffers, may have unexpected effects on stream health. We highlight the likely importance of intact or restored buffer

Shifted hot spots and nutrient imbalance in global fertilizer use for agriculture production in the past half century

Science.gov (United States)

Tian, H.; Lu, C.

2016-12-01

In addition to enhance agricultural productivity, synthetic nitrogen (N) and phosphorous (P) fertilizer application in croplands dramatically altered global nutrient budget, water quality, greenhouse gas balance, and their feedbacks to the climate system. However, due to the lack of geospatial fertilizer input data, current Earth system/land surface modeling studies have to ignore or use over-simplified data (e.g., static, spatially uniform fertilizer use) to characterize agricultural N and P input over decadal or century-long period. In this study, we therefore develop a global time-series gridded data of annual synthetic N and P fertilizer use rate in croplands, matched with HYDE 3,2 historical land use maps, at a resolution of 0.5º latitude by longitude during 1900-2013. Our data indicate N and P fertilizer use rates increased by approximately 8 times and 3 times, respectively, since the year 1961, when IFA (International Fertilizer Industry Association) and FAO (Food and Agricultural Organization) survey of country-level fertilizer input were available. Considering cropland expansion, increase of total fertilizer consumption amount is even larger. Hotspots of agricultural N fertilizer use shifted from the U.S. and Western Europe in the 1960s to East Asia in the early 21st century. P fertilizer input show the similar pattern with additional hotspot in Brazil. We find a global increase of fertilizer N/P ratio by 0.8 g N/g P per decade (phuman impacts on agroecosystem functions in the long run. Our data can serve as one of critical input drivers for regional and global assessment on agricultural productivity, crop yield, agriculture-derived greenhouse gas balance, global nutrient budget, land-to-aquatic nutrient loss, and ecosystem feedback to the climate system.

Role of nutrients in metabolic syndrome: a 2017 update

Directory of Open Access Journals (Sweden)

Kern HJ

2018-02-01

Full Text Available Hua J Kern, Susan Hazels Mitmesser The Nature’s Bounty Co., Ronkonkoma, NY, USA Abstract: Metabolic syndrome (MetS and its associated chronic disorders including cardiovascular disease and type 2 diabetes are public health concerns in the USA and worldwide. “Good health is an investment in economic growth,” and nutrition is one of the recommended preventive measures to manage these chronic diseases. However, it is unclear whether and to what extent nutrients could be beneficial to the improvement of MetS. To help answer this question, we performed a literature review of the emerging human data on single nutrients and MetS: PubMed was searched from January 1, 2005 to June 12, 2017, using a combination of the following keywords: “nutrient” OR “vitamin” OR “mineral” OR “nutraceutical” AND “metabolic syndrome.” The summary of literature comprises macronutrients (proteins/amino acids, fatty acids, fibers, and sugar, micronutrients (antioxidant vitamins, vitamin D, folate, magnesium, and chromium, polyphenols (flavonoids, resveratrol, isoflavones, and chlorogenic acid, and other compounds (α-lipoic acid, benfotiamine, fucoxanthin, policosanol, and stanols. Bearing a holistic approach in mind, we also highlighted select lifestyle factors that may contribute to MetS (such as circadian rhythm and nutrition in early life. Observational studies have generated positive evidence supporting the beneficial role of numerous nutrients in MetS. Although the results of some clinical trials are consistent with the observational data, causality is not always clear or consistent across trials. Both nutrition and health are complex and dynamic systems with a hierarchical nature. When we design confirmatory trials to investigate nutrient(s and MetS, instead of the traditional “single-nutrient” concept, it is worth considering a holistic approach to integrate groups or classes of nutrients, lifestyle influencers (ie, diet and physical

Main nutrient patterns and colorectal cancer risk in the European Prospective Investigation into Cancer and Nutrition study

NARCIS (Netherlands)

Moskal, Aurélie; Freisling, Heinz; Byrnes, Graham; Assi, Nada; Fahey, Michael T.; Jenab, Mazda; Ferrari, Pietro; Tjønneland, Anne; Petersen, Kristina EN; Dahm, Christina C.; Hansen, Camilla Plambeck; Affret, Aurélie; Boutron-Ruault, Marie Christine; Cadeau, Claire; Kühn, Tilman; Katzke, Verena; Iqbal, Khalid; Boeing, Heiner; Trichopoulou, Antonia; Bamia, Christina; Naska, Androniki; Masala, Giovanna; de Magistris, Maria Santucci; Sieri, Sabina; Tumino, Rosario; Sacerdote, Carlotta; Peeters, Petra H.; Bueno-de-Mesquita, Bas H.; Engeset, Dagrun; Licaj, Idlir; Skeie, Guri; Ardanaz, Eva; Buckland, Genevieve; Castaño, José M Huerta; Quirós, José R.; Amiano, Pilar; Molina-Portillo, Elena; Winkvist, Anna; Myte, Robin; Ericson, Ulrika; Sonestedt, Emily; Perez-Cornago, Aurora; Wareham, Nick; Khaw, Kay Tee; Huybrechts, Inge; Tsilidis, Konstantinos K.; Ward, Heather; Gunter, Marc J.; Slimani, Nadia

2016-01-01

Background:Much of the current literature on diet–colorectal cancer (CRC) associations focused on studies of single foods/nutrients, whereas less is known about nutrient patterns. We investigated the association between major nutrient patterns and CRC risk in participants of the European Prospective

Jointness through vessel capacity input in a multispecies fishery

DEFF Research Database (Denmark)

Hansen, Lars Gårn; Jensen, Carsten Lynge

2014-01-01

capacity. We develop a fixed but allocatable input model of purse seine fisheries capturing this particular type of jointness. We estimate the model for the Norwegian purse seine fishery and find that it is characterized by nonjointness, while estimations for this fishery using the standard models imply...... are typically modeled as either independent single species fisheries or using standard multispecies functional forms characterized by jointness in inputs. We argue that production of each species is essentially independent but that jointness may be caused by competition for fixed but allocable input of vessel...

WERF Nutrient Challenge investigates limits of nutrient removal technologies.

Science.gov (United States)

Neethling, J B; Clark, D; Pramanik, A; Stensel, H D; Sandino, J; Tsuchihashi, R

2010-01-01

The WERF Nutrient Challenge is a multi-year collaborative research initiative established in 2007 to develop and provide current information about wastewater treatment nutrients (specifically nitrogen and phosphorus in wastewater), their characteristics, and bioavailability in aquatic environments to help regulators make informed decisions. The Nutrient Challenge will also provide data on nutrient removal so that treatment facilities can select sustainable, cost-effective methods and technologies to meet permit limits. To meet these goals, the Nutrient Challenge has teamed with a wide array of utilities, agencies, consultants, universities and other researchers and practitioners to collaborate on projects that advance these goals. The Nutrient Challenge is focusing on a different approach to collaborating and leveraging resources (financial and intellectual) on research projects by targeting existing projects and research that correspond with its goals and funding those aspects that the Nutrient Challenge identified as a priority. Because the Nutrient Challenge is focused on collaboration, outreach is an absolutely necessary component of its effectiveness. Through workshops, webinars, a web portal and online compendium, published papers, and conference lectures, the Nutrient Challenge is both presenting important new information, and soliciting new partnerships.

Three-Dimensional Terahertz Coded-Aperture Imaging Based on Single Input Multiple Output Technology

Directory of Open Access Journals (Sweden)

Shuo Chen

2018-01-01

Full Text Available As a promising radar imaging technique, terahertz coded-aperture imaging (TCAI can achieve high-resolution, forward-looking, and staring imaging by producing spatiotemporal independent signals with coded apertures. In this paper, we propose a three-dimensional (3D TCAI architecture based on single input multiple output (SIMO technology, which can reduce the coding and sampling times sharply. The coded aperture applied in the proposed TCAI architecture loads either purposive or random phase modulation factor. In the transmitting process, the purposive phase modulation factor drives the terahertz beam to scan the divided 3D imaging cells. In the receiving process, the random phase modulation factor is adopted to modulate the terahertz wave to be spatiotemporally independent for high resolution. Considering human-scale targets, images of each 3D imaging cell are reconstructed one by one to decompose the global computational complexity, and then are synthesized together to obtain the complete high-resolution image. As for each imaging cell, the multi-resolution imaging method helps to reduce the computational burden on a large-scale reference-signal matrix. The experimental results demonstrate that the proposed architecture can achieve high-resolution imaging with much less time for 3D targets and has great potential in applications such as security screening, nondestructive detection, medical diagnosis, etc.

Reducing Nutrient Losses with Directed Fertilization of Degraded Soils

Science.gov (United States)

Menzies, E.; Walter, M. T.; Schneider, R.

2016-12-01

Degraded soils around the world are stunting agricultural productivity in places where people need it the most. In China, hundreds of years of agriculture and human activity have turned large swaths of productive grasslands into expanses of sandy soils where nothing can grow. Returning soils such as these to healthy productive landscapes is crucial to the livelihoods of rural families and to feeding the expanding population of China and the world at large. Buried wood chips can be used to improve the soils' water holding capacity but additional nutrient inputs are crucial to support plant growth and completely restore degraded soils in China and elsewhere. Improperly applied fertilizer can cause large fluxes of soluble nutrients such as nitrogen (N) and phosphorus (P) to pollute groundwater, and reach surface water bodies causing harmful algal blooms or eutrophication. Similarly, fertilization can create increases in nutrient losses in the form of greenhouse gases (GHGs). It is imperative that nutrient additions to this system be done in a way that fosters restoration and a return to productivity, but minimizes nutrient losses to adjacent surface water bodies and the atmosphere. The primary objective of this study is to characterize soluble and gaseous N and P losses from degraded sandy soils with wood chip and fertilizer amendments in order to identify optimal fertilization methods, frequencies, and quantities for soil restoration. A laboratory soil column study is currently underway to begin examining these questions results of this study will be presented at the Fall Meeting.

Recent land cover history and nutrient retention in riparian wetlands

Science.gov (United States)

Hogan, D.M.; Walbridge, M.R.

2009-01-01

Wetland ecosystems are profoundly affected by altered nutrient and sediment loads received from anthropogenic activity in their surrounding watersheds. Our objective was to compare a gradient of agricultural and urban land cover history during the period from 1949 to 1997, with plant and soil nutrient concentrations in, and sediment deposition to, riparian wetlands in a rapidly urbanizing landscape. We observed that recent agricultural land cover was associated with increases in Nitrogen (N) and Phosphorus (P) concentrations in a native wetland plant species. Conversely, recent urban land cover appeared to alter receiving wetland environmental conditions by increasing the relative availability of P versus N, as reflected in an invasive, but not a native, plant species. In addition, increases in surface soil Fe content suggests recent inputs of terrestrial sediments associated specifically with increasing urban land cover. The observed correlation between urban land cover and riparian wetland plant tissue and surface soil nutrient concentrations and sediment deposition, suggest that urbanization specifically enhances the suitability of riparian wetland habitats for the invasive species Japanese stiltgrass [Microstegium vimenium (Trinius) A. Camus]. ?? 2009 Springer Science+Business Media, LLC.

Improving fermented quality of cider vinegar via rational nutrient feeding strategy.

Science.gov (United States)

Qi, Zhengliang; Dong, Die; Yang, Hailin; Xia, Xiaole

2017-06-01

This work aimed to find a rational nutrient feeding strategy for cider vinegar fermentation based on adequate information on the nutritional requirement of acetic acid bacteria. Through single nutrient lack experiment assay, necessary nutrient recipe for Acetobacter pasteurianus CICIM B7003 in acetous fermentation was confirmed. Compounds from the essential nutrient recipe were tested further to find out the key substrates significantly influencing cider vinegar fermentation. The findings showed that aspartate, glutamate, proline and tryptophan should be considered in detail for optimizing nutritional composition of cider. Finally, a nutrient feeding strategy that simultaneously adds proline, glutamate, aspartate and tryptophan to form final concentrations of 0.02g/L, 0.03g/L, 0.01g/L and 0.005g/L in cider was achieved by orthogonal experiment design. Comparing to the original fermentation, the yield of acetic acid from alcohol reached 93.3% and the concentration of most volatile flavor compounds increased with the rational nutrient feeding strategy. Copyright © 2016 Elsevier Ltd. All rights reserved.

PERMODELAN INDEKS HARGA KONSUMEN INDONESIA DENGAN MENGGUNAKAN MODEL INTERVENSI MULTI INPUT

KAUST Repository

Novianti, Putri Wikie; Suhartono, Suhartono

2017-01-01

-searches that have been done are only contain of an intervention with single input, ei-ther step or pulse function. Multi input intervention was used in Indonesia CPI case because there are some events which are expected effecting CPI. Based on the result, those

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

Science.gov (United States)

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.

Compost supplementation with nutrients and microorganisms in composting process.

Science.gov (United States)

Sánchez, Óscar J; Ospina, Diego A; Montoya, Sandra

2017-11-01

The composting is an aerobic, microorganism-mediated, solid-state fermentation process by which different organic materials are transformed into more stable compounds. The product obtained is the compost, which contributes to the improvement of physical, chemical and microbiological properties of the soil. However, the compost usage in agriculture is constrained because of its long-time action and reduced supply of nutrients to the crops. To enhance the content of nutrients assimilable by the plants in the compost, its supplementation with nutrients and inoculation with microorganisms have been proposed. The objective of this work was to review the state of the art on compost supplementation with nutrients and the role played by the microorganisms involved (or added) in their transformation during the composting process. The phases of composting are briefly compiled and different strategies for supplementation are analyzed. The utilization of nitrogenous materials and addition of microorganisms fixing nitrogen from the atmosphere or oxidizing ammonia into more assimilable for plants nitrogenous forms are analyzed. Several strategies for nitrogen conservation during composting are presented as well. The supplementation with phosphorus and utilization of microorganisms solubilizing phosphorus and potassium are also discussed. Main groups of microorganisms relevant during the composting process are described as well as most important strategies to identify them. In general, the development of this type of nutrient-enriched bio-inputs requires research and development not only in the supplementation of compost itself, but also in the isolation and identification of microorganisms and genes allowing the degradation and conversion of nitrogenous substances and materials containing potassium and phosphorus present in the feedstocks undergoing the composting process. In this sense, most important research trends and strategies to increase nutrient content in the compost

Resuspension and estuarine nutrient cycling: insights from the Neuse River Estuary

Directory of Open Access Journals (Sweden)

D. R. Corbett

2010-10-01

Full Text Available For at least the past several decades, North Carolina's Neuse River Estuary (NRE has been subject to water quality problems relating to increased eutrophication. Research initiated in the past several years have addressed the nutrient processes of the water column and the passive diffusion processes of the benthic sedimentary environment. Resuspension of bottom sediments, by bioturbation, tides, or winds, may also have a significant effect on the flux of nutrients in an estuarine system These processes can result in the advective transport of sediment porewater, rich with nitrogen, phosphorus and carbon, into the water column. Thus, estimates of nutrient and carbon inputs from the sediments may be too low.

This study focused on the potential change in bottom water nutrient concentrations associated with measured resuspension events. Previous research used short-lived radionuclides and meteorological data to characterize the sediment dynamics of the benthic system of the estuary. These techniques in conjunction with the presented porewater inventories allowed evaluation of the depth to which sediments have been disturbed and the advective flux of nutrients to the water column. The largest removal episode occurred in the lower NRE as the result of a wind event and was estimated that the top 2.2 cm of sediment and corresponding porewater were removed. NH₄⁺ advective flux (resuspended was 2 to 6 times greater than simply diffusion. Phosphate fluxes were estimated to be 15 times greater than the benthic diffusive flux. Bottom water conditions with elevated NH₄⁺ and PO₄³⁻ indicate that nutrients stored in the sediments continue to play an important role in overall water quality and this study suggests that the advective flux of nutrients to the water column is critical to understand estuarine nutrient cycling.

A dynamic growth model for prediction of nutrient partitioning and manure production in growing–finishing pigs: Model development and evaluation

DEFF Research Database (Denmark)

Danfær, Allan Christian; Jørgensen, Henry; Kebreab, E

2015-01-01

trials using growing–finishing pig diets that had a wide range of nutrient chemical composition. Nutrient and water excretion were quantified using the principle of mass conservation. The average daily observed and predicted manure production was 3.79 and 3.99 kg/d, respectively, with a RMSPE of 0.49 kg......Nutrient loading and air emissions from swine operations raise environmental concerns. The objective of the study was to describe and evaluate a mathematical model (Davis Swine Model) of nutrient partitioning and predict manure excretion and composition on a daily basis. State variables...... the body constituent pools. It was assumed that fluxes of metabolites follow saturation kinetics, depending on metabolite concentrations. The main inputs to the model were diet nutrient composition, feed intake, water-to-feed ratio, and initial BW. First, the model was challenged with nutrient partitioning...

Interactive effects of vertical mixing, nutrients and ultraviolet radiation: in situ photosynthetic responses of phytoplankton from high mountain lakes of Southern Europe

Science.gov (United States)

Helbling, E. W.; Carrillo, P.; Medina-Sanchez, J. M.; Durán, C.; Herrera, G.; Villar-Argaiz, M.; Villafañe, V. E.

2012-07-01

Global change, together with human activities had resulted in increasing amounts of organic material (including nutrients) received by water bodies. This input further attenuates the penetration of solar radiation leading to the view that opaque lakes are more "protected" from solar ultraviolet radiation (UVR) than clear ones. Vertical mixing, however, complicates this view as cells are exposed to fluctuating radiation regimes, which effects have in general been neglected. Even more, the combined impacts of mixing, together with those of UVR and nutrients input are virtually unknown. In this study, we carried out in situ experiments in three high mountain lakes of Spain (Lake Enol in Asturias, and lakes Las Yeguas and La Caldera in Granada) to determine the combined effects of these three variables associated to global change on photosynthetic responses of natural phytoplankton communities. The experimentation consisted in all possible combinations of the following treatments: (a) solar radiation: UVR + PAR (280-700 nm) versus PAR alone (400-700 nm); (b) nutrient addition (phosphorus (P) and nitrogen (N)): ambient versus addition (P to reach to a final concentration of 30 μg P l-1, and N to reach a N : P molar ratio of 31) and, (c) mixing: mixed (one rotation from surface to 3 m depth (speed of 1 m every 4 min, total of 10 cycles) versus static. Our findings suggest that under in situ nutrient conditions there is a synergistic effect between vertical mixing and UVR, increasing phytoplankton photosynthetic inhibition and EOC from opaque lakes as compared to algae that received constant mean irradiance within the epilimnion. The opposite occurs in clear lakes where antagonistic effects were determined, with mixing partially counteracting the negative effects of UVR. Nutrients input mimicking atmospheric pulses from Saharan dust, reversed this effect and clear lakes became more inhibited during mixing, while opaque lakes benefited from the fluctuating irradiance

Direct and indirect effects of vertical mixing, nutrients and ultraviolet radiation on the bacterioplankton metabolism in high-mountain lakes from southern Europe

Science.gov (United States)

Durán, C.; Medina-Sánchez, J. M.; Herrera, G.; Villar-Argaiz, M.; Villafañe, V. E.; Helbling, E. W.; Carrillo, P.

2014-05-01

As a consequence of global change, modifications in the interaction among abiotic stressors on aquatic ecosystems have been predicted. Among other factors, UVR transparency, nutrient inputs and shallower epilimnetic layers could alter the trophic links in the microbial food web. Currently, there are some evidences of higher sensitiveness of aquatic microbial organisms to UVR in opaque lakes. Our aim was to assess the interactive direct and indirect effects of UVR (through the excretion of organic carbon - EOC - by algae), mixing regime and nutrient input on bacterial metabolism. We performed in situ short-term experiments under the following treatments: full sunlight (UVR + PAR, >280 nm) vs. UVR exclusion (PAR only, >400 nm); ambient vs. nutrient addition (phosphorus (P; 30 μg PL-1) and nitrogen (N; up to final N : P molar ratio of 31)); and static vs. mixed regime. The experiments were conducted in three high-mountain lakes of Spain: Enol [LE], Las Yeguas [LY] and La Caldera [LC] which had contrasting UVR transparency characteristics (opaque (LE) vs. clear lakes (LY and LC)). Under ambient nutrient conditions and static regimes, UVR exerted a stimulatory effect on heterotrophic bacterial production (HBP) in the opaque lake but not in the clear ones. Under UVR, vertical mixing and nutrient addition HBP values were lower than under the static and ambient nutrient conditions, and the stimulatory effect that UVR exerted on HBP in the opaque lake disappeared. By contrast, vertical mixing and nutrient addition increased HBP values in the clear lakes, highlighting for a photoinhibitory effect of UVR on HBP. Mixed regime and nutrient addition resulted in negative effects of UVR on HBP more in the opaque than in the clear lakes. Moreover, in the opaque lake, bacterial respiration (BR) increased and EOC did not support the bacterial carbon demand (BCD). In contrast, bacterial metabolic costs did not increase in the clear lakes and the increased nutrient availability even

Seasonal steady-state budgets of nutrients and stoichiometric calculations in an Eastern Mediterranean lagoon (Papas Lagoon-Greece

Directory of Open Access Journals (Sweden)

E. KRASAKOPOULOU

2011-01-01

Full Text Available The Papas Lagoon is an enclosed, small shallow water body in western Greece. The lagoon is naturally affected by eutrophication phenomena, but occasionally during the summer season, dystrophic crises occur, related to the decomposition of large beds of macroalgae. Physicochemical data collected monthly, from June 1998 to September 1999, were compiled and coupled with historical meteorological data, in order to construct seasonal water, salt and nutrients budgets using a single box single layer LOICZ model. Nutrients and other hydrochemical parameters exhibit great spatial and temporal variations. The non-conservative dissolved inorganic phosphorus flux (ΔDIP is always positive, thus indicating that the system acts as a net source of DIP for the adjacent coastal waters. Higher values were estimated  uring summer and autumn, probably due to organic matter mineralisation and release of DIP from surficial sediments in the reduced environment. In contrast to the ΔDIP, the non-conservative balance of dissolved inorganic nitrogen (ΔDIN is negative for most of the year, except for the summer, indicating the dominance of DIN removal processes in the Papas Lagoon. The Ulva growth and decomposition processes seem likely to be of essential importance for the evaluation of the non-conservative DIN fluxes. During the investigated period the amount of organic carbon respired and mineralized is greater than that produced by gross photosynthesis and the Papas Lagoon is a net heterotrophic system. Losses of DIN via denitrification appear to dominate over its inputs through nitrogen fixation throughout the year.

Mitigating cyanobacterial harmful algal blooms in aquatic ecosystems impacted by climate change and anthropogenic nutrients.

Science.gov (United States)

Paerl, Hans W; Gardner, Wayne S; Havens, Karl E; Joyner, Alan R; McCarthy, Mark J; Newell, Silvia E; Qin, Boqiang; Scott, J Thad

2016-04-01

Mitigating the global expansion of cyanobacterial harmful blooms (CyanoHABs) is a major challenge facing researchers and resource managers. A variety of traditional (e.g., nutrient load reduction) and experimental (e.g., artificial mixing and flushing, omnivorous fish removal) approaches have been used to reduce bloom occurrences. Managers now face the additional effects of climate change on watershed hydrologic and nutrient loading dynamics, lake and estuary temperature, mixing regime, internal nutrient dynamics, and other factors. Those changes favor CyanoHABs over other phytoplankton and could influence the efficacy of control measures. Virtually all mitigation strategies are influenced by climate changes, which may require setting new nutrient input reduction targets and establishing nutrient-bloom thresholds for impacted waters. Physical-forcing mitigation techniques, such as flushing and artificial mixing, will need adjustments to deal with the ramifications of climate change. Here, we examine the suite of current mitigation strategies and the potential options for adapting and optimizing them in a world facing increasing human population pressure and climate change. Copyright © 2015 Elsevier B.V. All rights reserved.

Nutrients fluxes from groundwater discharge into Mangueira Lagoon (Rio Grande do Sul, Brazil); Fluxos de nutrientes associados as descargas de agua subterranea para a Lagoa Mangueira (Rio Grande do Sul, Brasil)

Energy Technology Data Exchange (ETDEWEB)

Andrade, Carlos F.F.; Niencheski, Luis F.H.; Attisano, Karina K.; Milani, Marcio R., E-mail: pgofcfa@furg.br [Instituto de Oceanografia, Universidade Federal do Rio Grande, Campus Carreiros, Rio Grande, RS (Brazil); Santos, Isaac R. [Department of Oceanography, Florida State University, Tallahassee, FL (United States); Milani, Idel C. [Departamento de Engenharia Hidrica, Centro de Desenvolvimento Tecnologico, Universidade Federal de Pelotas, Campus Porto, Pelotas, RS (Brazil)

2012-07-01

This study assesses the importance of groundwater discharge to dissolved nutrient levels in Mangueira Lagoon. A transect of an irrigation canal in the margin of Lagoon demonstrated a strong geochemical gradient due to high groundwater inputs in this area. Using {sup 222}Rn as a quantitative groundwater tracer, we observed that the flux of dissolved inorganic nitrogen (DIN), silicate and phosphate (1178 and 1977; 26190 and 35652; 167 and 188 mol d{sup -1} for winter and summer, respectively) can continually supply/sustain primary production. The irrigation canals act as an artificial underground tributary and represent a new source of nutrients to coastal lagoons. (author)

Crop Breeding for Low Input Agriculture: A Sustainable Response to Feed a Growing World Population

Directory of Open Access Journals (Sweden)

Vagner A. Benedito

2011-10-01

Full Text Available World population is projected to reach its maximum (~10 billion people by the year 2050. This 45% increase of the current world population (approaching seven billion people will boost the demand for food and raw materials. However, we live in a historical moment when supply of phosphate, water, and oil are at their peaks. Modern agriculture is fundamentally based on varieties bred for high performance under high input systems (fertilizers, water, oil, pesticides, which generally do not perform well under low-input situations. We propose a shift of research goals and plant breeding objectives from high-performance agriculture at high-energy input to those with an improved rationalization between yield and energy input. Crop breeding programs that are more focused on nutrient economy and local environmental fitness will help reduce energy demands for crop production while still providing adequate amounts of high quality food as global resources decline and population is projected to increase.

Use of composts to improve soil properties and crop productivity under low input agricultural system in West Africa

NARCIS (Netherlands)

Ouédraogo, E.; Mando, A.; Zombré, N.P.

2000-01-01

Lack of adequate nutrient supply and poor soil structure are the principal constraints to crop production under low input agriculture systems of West Africa. Experiments at two sites (Mediga and Yimtenga) were conducted in Burkina Faso to assess the impact of compost on improving crop production and

Integrated nutrients management for 'desi' cotton

International Nuclear Information System (INIS)

Qazi, M.A.; Akram, M.; Ahmad, N.; Khattak, M.A.

2007-01-01

Intensive cropping with no return of crop residues and other organic inputs result in the loss of soil organic matter (SOM) and nutrient supply in (Desi) cotton-wheat cropping system in Pakistan. For appraisal of problem and finding solution to sustainability, we evaluated six treatments comprised of two fertilizer doses and three management techniques over a period of three years (2003-05) monitoring their effects on seed cotton yield and soil fertility. The techniques included chemical fertilizers, municipal solid waste manure (MSWM) integrated with chemical fertilizers in 1:4 ratios with, and without pesticides. The results revealed that cotton yields. Were enhanced by 19% due to site-specific fertilizer dose over conventional dose. Ignoring weeds control by means of herbicided application resulted in 5% decrease of seed cotton yield in IPNM technique positive effect of MSWM integration was noted on soil test phosphorus and SOM. Site-specific fertilizer application and integrated plant nutrient management by MSWM proved their suitability as the techniques not only improve soil quality in terms of sustained levels of organic matter and phosphorus but also provide a safe way of waste disposal. (author)

Evidence of chronic anthropogenic nutrient within coastal lagoon reefs adjacent to urban and tourism centers, Kenya: A stable isotope approach.

Science.gov (United States)

Mwaura, Jelvas; Umezawa, Yu; Nakamura, Takashi; Kamau, Joseph

2017-06-30

The source of anthropogenic nutrient and its spatial extent in three fringing reefs with differing human population gradients in Kenya were investigated using stable isotope approaches. Nutrient concentrations and nitrate-δ 15 N in seepage water indicated that population density and tourism contributed greatly to the extent of nutrient loading to adjacent reefs. Although water-column nutrient analyses did not show any significant difference among the reefs, higher δ 15 N and N contents in macrophytes showed terrestrial nutrients affected primary producers in onshore areas in Nyali and Bamburi reefs, but were mitigated by offshore water intrusion especially at Nyali. On the offshore reef flat, where the same species of macroalgae were not available, complementary use of δ 15 N in sedimentary organic matter suggested inputs of nutrients originated from the urban city of Mombasa. If population increases in the future, nutrient conditions in the shallower reef, Vipingo, may be dramatically degraded due to lower water exchange ratio. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of mountain agriculture on nutrient cycling at upstream watersheds

Science.gov (United States)

Lin, T.-C.; Shaner, P. L.; Wang, L.-J.; Shih, Y.-T.; Wang, C.-P.; Huang, G.-H.; Huang, J.-C.

2015-05-01

The expansion of agriculture to rugged mountains can exacerbate negative impacts of agriculture activities on ecosystem function. In this study, we monitored streamwater chemistry of four watersheds with varying proportions of agricultural lands (0.4, 3, 17, 22%) and rainfall chemistry of two of the four watersheds at Feitsui Reservoir Watershed in northern Taiwan to examine the effects of agriculture on watershed nutrient cycling. We found that the greater the proportions of agricultural lands, the higher the ion concentrations, which is evident for fertilizer-associated ions (NO3-, K+) but not for ions that are rich in soils (SO42-, Ca2+, Mg2+), suggesting that agriculture enriched fertilizer-associated nutrients in streamwater. The watershed with the highest proportion of agricultural lands had higher concentrations of ions in rainfall and lower nutrient retention capacity (i.e. higher output-input ratio of ions) compared to the relatively pristine watershed, suggesting that agriculture can influence atmospheric deposition of nutrients and a system's ability to retain nutrients. Furthermore, we found that a forested watershed downstream of agricultural activities can dilute the concentrations of fertilizer-associated ions (NO3-, K+) in streamwater by more than 70%, indicating that specific landscape configurations help mitigate nutrient enrichment to aquatic systems. We estimated that agricultural lands at our study site contributed approximately 400 kg ha-1 yr-1 of NO3-N and 260 kg ha-1 yr-1 of PO4-P output via streamwater, an order of magnitude greater than previously reported around the globe and can only be matched by areas under intense fertilizer use. Furthermore, we re-constructed watershed nutrient fluxes to show that excessive leaching of N and P, and additional loss of N to the atmosphere via volatilization and denitrification, can occur under intense fertilizer use. In summary, this study demonstrated the pervasive impacts of agriculture activities

Investigation on single carbon atom transporting through the single-walled carbon nanotube by MD simulation

International Nuclear Information System (INIS)

Ding Yinfeng; Zhang Zhibin; Ke Xuezhi; Zhu Zhiyuan; Zhu Dezhang; Wang Zhenxia; Xu Hongjie

2005-01-01

The single carbon atom transporting through the single-walled carbon nanotube has been studied by molecular-dynamics (MD) simulation. We got different trajectories of the carbon atom by changing the input parameters. The simulation results indicate that the single carbon atom with low energy can transport through the carbon nanotube under some input conditions and result in different trajectories being straight line or 'rosette' or circular. (authors)

Response of the soil microbial community and soil nutrient bioavailability to biomass harvesting and reserve tree retention in northern Minnesota aspen-dominated forests

Science.gov (United States)

Tera E. Lewandowski; Jodi A. Forrester; David J. Mladenoff; Anthony W. D' Amato; Brian J. Palik

2016-01-01

Intensive forest biomass harvesting, or the removal of harvesting slash (woody debris from tree branches and tops) for use as biofuel, has the potential to negatively affect the soil microbial community (SMC) due to loss of carbon and nutrient inputs from the slash, alteration of the soil microclimate, and increased nutrient leaching. These effects could result in...

Benthic Nutrient Fluxes from Mangrove Sediments of an Anthropogenically Impacted Estuary in Southern China

Directory of Open Access Journals (Sweden)

David Kaiser

2015-06-01

Full Text Available Mangroves serve as either sinks or sources for inorganic and organic nutrients and can mitigate anthropogenic nutrient pollution, control the production in adjacent systems, and prevent eutrophication. To better understand the nutrient dynamics in a subtropical mangrove, we employed a three-way approach in the Nanliu River Estuary, southern China: Pore water profiles and sediment incubations revealed benthic early diagenesis as well as sediment–water exchange of dissolved nutrients and oxygen, while tidal sampling of estuarine and mangrove water identified source and sink functions of the entire mangrove forest. Fluxes of oxygen during incubations were always directed into the sediment, indicating heterotrophy of the system. There was a net uptake of dissolved inorganic nitrogen, mainly caused by nitrate influx, while ammonium and nitrite showed variable flux direction. Despite high pore water concentrations, phosphate and silica showed net uptake. Fluxes of dissolved organic carbon were generally low except for high efflux in the dark following a storm event. Due to the combination of small forest area and strong anthropogenic nutrient input, the net sink function for dissolved nitrogen and phosphorus provides no significant buffer against the eutrophication of coastal waters.

The impact of biotic/abiotic interfaces in mineral nutrient cycling: A study of soils of the Santa Cruz chronosequence, California

Science.gov (United States)

White, A.F.; Schulz, M.S.; Vivit, D.V.; Bullen, T.D.; Fitzpatrick, J.

2012-01-01

Biotic/abiotic interactions between soil mineral nutrients and annual grassland vegetation are characterized for five soils in a marine terrace chronosequence near Santa Cruz, California. A Mediterranean climate, with wet winters and dry summers, controls the annual cycle of plant growth and litter decomposition, resulting in net above-ground productivities of 280-600gm -2yr -1. The biotic/abiotic (A/B) interface separates seasonally reversible nutrient gradients, reflecting biological cycling in the shallower soils, from downward chemical weathering gradients in the deeper soils. The A/B interface is pedologically defined by argillic clay horizons centered at soil depths of about one meter which intensify with soil age. Below these horizons, elevated solute Na/Ca, Mg/Ca and Sr/Ca ratios reflect plagioclase and smectite weathering along pore water flow paths. Above the A/B interface, lower cation ratios denote temporal variability due to seasonal plant nutrient uptake and litter leaching. Potassium and Ca exhibit no seasonal variability beneath the A/B interface, indicating closed nutrient cycling within the root zone, whereas Mg variability below the A/B interface denotes downward leakage resulting from higher inputs of marine aerosols and lower plant nutrient requirements.The fraction of a mineral nutrient annually cycled through the plants, compared to that lost from pore water discharge, is defined their respective fluxes F j,plants=q j,plants/(q j,plants+q j,discharge) with average values for K and Ca (F K,plants=0.99; F Ca,plants=0.93) much higher than for Mg and Na (F Mg,plants 0.64; F Na,plants=0.28). The discrimination against Rb and Sr by plants is described by fractionation factors (K Sr/Ca=0.86; K Rb/K=0.83) which are used in Rayleigh fractionation-mixing calculations to fit seasonal patterns in solute K and Ca cycling. K Rb/K and K24Mg/22Mg values (derived from isotope data in the literature) fall within fractionation envelopes bounded by inputs from

Brain Emotional Learning Based Intelligent Decoupler for Nonlinear Multi-Input Multi-Output Distillation Columns

Directory of Open Access Journals (Sweden)

M. H. El-Saify

2017-01-01

Full Text Available The distillation process is vital in many fields of chemical industries, such as the two-coupled distillation columns that are usually highly nonlinear Multi-Input Multi-Output (MIMO coupled processes. The control of MIMO process is usually implemented via a decentralized approach using a set of Single-Input Single-Output (SISO loop controllers. Decoupling the MIMO process into group of single loops requires proper input-output pairing and development of decoupling compensator unit. This paper proposes a novel intelligent decoupling approach for MIMO processes based on new MIMO brain emotional learning architecture. A MIMO architecture of Brain Emotional Learning Based Intelligent Controller (BELBIC is developed and applied as a decoupler for 4 input/4 output highly nonlinear coupled distillation columns process. Moreover, the performance of the proposed Brain Emotional Learning Based Intelligent Decoupler (BELBID is enhanced using Particle Swarm Optimization (PSO technique. The performance is compared with the PSO optimized steady state decoupling compensation matrix. Mathematical models of the distillation columns and the decouplers are built and tested in simulation environment by applying the same inputs. The results prove remarkable success of the BELBID in minimizing the loops interactions without degrading the output that every input has been paired with.

Past and future trends in grey water footprints of anthropogenic nitrogen and phosphorus inputs to major world rivers

NARCIS (Netherlands)

Liu, C.; Kroeze, C.; Hoekstra, Arjen Ysbert; Gerbens-Leenes, Winnie

2012-01-01

The grey water footprint (GWF) is an indicator of aquatic pollution. We calculate past and future trends in GWFs related to anthropogenic nitrogen (N) and phosphorus (P) inputs into major rivers around the world. GWFs were calculated from past, current and future nutrient loads in river basins using

Root carbon input in organic and inorganic fertilizer-based systems

DEFF Research Database (Denmark)

Chirinda, Ngoni; Olesen, Jørgen E; Porter, John

2012-01-01

C input to remain scant. This study aimed at determining macro-root C input and topsoil root related respiration in response to nutrient management and soil fertility building measures. Methods We sampled roots and shoots of cereals and catch crops in inorganic and organic fertilizer-based arable...... season of winter wheat by subtracting soil respiration from soil with and without exclusion of roots. Results Catch crop roots accounted for more than 40 % of total plant C. For spring barley in 2008 and spring wheat in 2010, root C was higher in the organic than in the inorganic fertilizer-based systems...... was higher (31–131 %) in inorganic than in organic fertilizer-based systems. Conclusions Our findings show that macro-roots of both cereal crops and catch crops play a relatively larger role in organically managed systems than in mineral fertilizer based systems; and that the use of fixed biomass S/R ratios...

Isotopic signatures of eelgrass (Zostera marina L.) as bioindicator of anthropogenic nutrient input in the western Baltic Sea

International Nuclear Information System (INIS)

Schubert, Philipp R.; Karez, Rolf; Reusch, Thorsten B.H.; Dierking, Jan

2013-01-01

Highlights: • Anthropogenic nitrogen (N) inputs are a global problem, but difficult to quantify. • We tested the use of eelgrass δ 15 N as proxy of such inputs in the Baltic Sea. • The method revealed distinct spatial patterns in sewage N across a eutrophic bay. • Traditional eutrophication measures corroborated the results from δ 15 N values. • Eelgrass δ 15 N ratios have high potential as proxy of sewage-derived N in the Baltic. -- Abstract: Eutrophication is a global environmental problem. Better management of this threat requires more accurate assessments of anthropogenic nitrogen (N) inputs to coastal systems than can be obtained with traditional measures. Recently, primary producer N isotopic signatures have emerged as useful proxy of such inputs. Here, we demonstrated for the first time the applicability of this method using the widespread eelgrass (Zostera marina) in the highly eutrophic Baltic Sea. Spatial availability of sewage N across a bay with one major sewage outflow predicted by eelgrass δ 15 N was high near and downstream of the outflow compared to upstream, but returned to upstream levels within 4 km downstream from the outfall. General conclusions were corroborated by traditional eutrophication measures, but in contrast to these measures were fully quantitative. Eelgrass N isotope ratios therefore show high potential for coastal screens of eutrophication in the Baltic Sea, and in other areas with eelgrass meadows

Nutrient intake and nutrient patterns and risk of lung cancer among heavy smokers: results from the COSMOS screening study with annual low-dose CT

International Nuclear Information System (INIS)

Gnagnarella, Patrizia; Maisonneuve, Patrick; Bellomi, Massimo; Rampinelli, Cristiano; Bertolotti, Raffaella; Spaggiari, Lorenzo; Palli, Domenico; Veronesi, Giulia

2013-01-01

The role of nutrients in lung cancer aetiology remains controversial and has never been evaluated in the context of screening. Our aim was to investigate the role of single nutrients and nutrient patterns in the aetiology of lung cancer in heavy smokers. Asymptomatic heavy smokers (≥20 pack-years) were invited to undergo annual low-dose computed tomography. We assessed diet using a self-administered food frequency questionnaire and collected information on multivitamin supplement use. We performed principal component analysis identifying four nutrient patterns and used Cox proportional Hazards regression to assess the association between nutrients and nutrients patterns and lung cancer risk. During a mean follow-up of 5.7 years, 178 of 4,336 participants were diagnosed with lung cancer by screening. We found a significant risk reduction of lung cancer with increasing vegetable fat consumption (HR for highest vs. lowest quartile = 0.50, 95 % CI = 0.31–0.80; P-trend = 0.02). Participants classified in the high “vitamins and fiber” pattern score had a significant risk reduction of lung cancer (HR = 0.57; 95 % CI = 0.36–0.90, P-trend = 0.01). Among heavy smokers enrolled in a screening trial, high vegetable fat intake and adherence to the “vitamin and fiber” nutrient pattern were associated with reduced lung cancer incidence.

Multi-Input Convolutional Neural Network for Flower Grading

Directory of Open Access Journals (Sweden)

Yu Sun

2017-01-01

Full Text Available Flower grading is a significant task because it is extremely convenient for managing the flowers in greenhouse and market. With the development of computer vision, flower grading has become an interdisciplinary focus in both botany and computer vision. A new dataset named BjfuGloxinia contains three quality grades; each grade consists of 107 samples and 321 images. A multi-input convolutional neural network is designed for large scale flower grading. Multi-input CNN achieves a satisfactory accuracy of 89.6% on the BjfuGloxinia after data augmentation. Compared with a single-input CNN, the accuracy of multi-input CNN is increased by 5% on average, demonstrating that multi-input convolutional neural network is a promising model for flower grading. Although data augmentation contributes to the model, the accuracy is still limited by lack of samples diversity. Majority of misclassification is derived from the medium class. The image processing based bud detection is useful for reducing the misclassification, increasing the accuracy of flower grading to approximately 93.9%.

Investigation of nutrient feeding strategies in a countercurrent mixed-acid multi-staged fermentation: experimental data.

Science.gov (United States)

Smith, Aaron Douglas; Lockman, Nur Ain; Holtzapple, Mark T

2011-06-01

Nutrients are essential for microbial growth and metabolism in mixed-culture acid fermentations. Understanding the influence of nutrient feeding strategies on fermentation performance is necessary for optimization. For a four-bottle fermentation train, five nutrient contacting patterns (single-point nutrient addition to fermentors F1, F2, F3, and F4 and multi-point parallel addition) were investigated. Compared to the traditional nutrient contacting method (all nutrients fed to F1), the near-optimal feeding strategies improved exit yield, culture yield, process yield, exit acetate-equivalent yield, conversion, and total acid productivity by approximately 31%, 39%, 46%, 31%, 100%, and 19%, respectively. There was no statistical improvement in total acid concentration. The traditional nutrient feeding strategy had the highest selectivity and acetate-equivalent selectivity. Total acid productivity depends on carbon-nitrogen ratio.

Automated Liquid-Level Control of a Nutrient Reservoir for a Hydroponic System

Science.gov (United States)

Smith, Boris; Asumadu, Johnson A.; Dogan, Numan S.

1997-01-01

A microprocessor-based system for control of the liquid level of a nutrient reservoir for a plant hydroponic growing system has been developed. The system uses an ultrasonic transducer to sense the liquid level or height. A National Instruments' Multifunction Analog and Digital Input/Output PC Kit includes NI-DAQ DOS/Windows driver software for an IBM 486 personal computer. A Labview Full Development system for Windows is the graphical programming system being used. The system allows liquid level control to within 0.1 cm for all levels tried between 8 and 36 cm in the hydroponic system application. The detailed algorithms have been developed and a fully automated microprocessor based nutrient replenishment system has been described for this hydroponic system.

Nutrient cycling strategies.

NARCIS (Netherlands)

Breemen, van N.

1995-01-01

This paper briefly reviews pathways by which plants can influence the nutrient cycle, and thereby the nutrient supply of themselves and of their competitors. Higher or lower internal nutrient use efficiency positively feeds back into the nutrient cycle, and helps to increase or decrease soil

Technical Note: A comparison of two empirical approaches to estimate in-stream net nutrient uptake

Science.gov (United States)

von Schiller, D.; Bernal, S.; Martí, E.

2011-04-01

To establish the relevance of in-stream processes on nutrient export at catchment scale it is important to accurately estimate whole-reach net nutrient uptake rates that consider both uptake and release processes. Two empirical approaches have been used in the literature to estimate these rates: (a) the mass balance approach, which considers changes in ambient nutrient loads corrected by groundwater inputs between two stream locations separated by a certain distance, and (b) the spiralling approach, which is based on the patterns of longitudinal variation in ambient nutrient concentrations along a reach following the nutrient spiralling concept. In this study, we compared the estimates of in-stream net nutrient uptake rates of nitrate (NO3) and ammonium (NH4) and the associated uncertainty obtained with these two approaches at different ambient conditions using a data set of monthly samplings in two contrasting stream reaches during two hydrological years. Overall, the rates calculated with the mass balance approach tended to be higher than those calculated with the spiralling approach only at high ambient nitrogen (N) concentrations. Uncertainty associated with these estimates also differed between both approaches, especially for NH4 due to the general lack of significant longitudinal patterns in concentration. The advantages and disadvantages of each of the approaches are discussed.

Diagnosis of nutrient imbalances with vector analysis in agroforestry systems.

Science.gov (United States)

Isaac, Marney E; Kimaro, Anthony A

2011-01-01

Agricultural intensification has had unintended environmental consequences, including increased nutrient leaching and surface runoff and other agrarian-derived pollutants. Improved diagnosis of on-farm nutrient dynamics will have the advantage of increasing yields and will diminish financial and environmental costs. To achieve this, a management support system that allows for site-specific rapid evaluation of nutrient production imbalances and subsequent management prescriptions is needed for agroecological design. Vector diagnosis, a bivariate model to depict changes in yield and nutritional response simultaneously in a single graph, facilitates identification of nutritional status such as growth dilution, deficiency, sufficiency, luxury uptake, and toxicity. Quantitative data from cocoa agroforestry systems and pigeonpea intercropping trials in Ghana and Tanzania, respectively, were re-evaluated with vector analysis. Relative to monoculture, biomass increase in cocoa ( L.) under shade (35-80%) was accompanied by a 17 to 25% decline in P concentration, the most limiting nutrient on this site. Similarly, increasing biomass with declining P concentrations was noted for pigeonpea [ (L). Millsp.] in response to soil moisture availability under intercropping. Although vector analysis depicted nutrient responses, the current vector model does not consider non-nutrient resource effects on growth, such as ameliorated light and soil moisture, which were particularly active in these systems. We revisit and develop vector analysis into a framework for diagnosing nutrient and non-nutrient interactions in agroforestry systems. Such a diagnostic technique advances management decision-making by increasing nutrient precision and reducing environmental issues associated with agrarian-derived soil contamination. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

Dietary influences on nutrient partitioning and anatomical body composition of growing pigs; modelling and experimental approaches

NARCIS (Netherlands)

Halas, V.

2004-01-01

Prediction of pig performance from data on nutrient intake and animal properties makes it easier to obtain a better productivity. It provides tools to arrive at desired outputs, or to calculate required inputs. Thus it enables production to be flexible, safe and less erratic. It is to be expected

Utilizing Dietary Micronutrient Ratios in Nutritional Research May be More Informative than Focusing on Single Nutrients

Directory of Open Access Journals (Sweden)

Owen J. Kelly

2018-01-01

Full Text Available The 2015 US dietary guidelines advise the importance of good dietary patterns for health, which includes all nutrients. Micronutrients are rarely, if ever, consumed separately, they are not tissue specific in their actions and at the molecular level they are multitaskers. Metabolism functions within a seemingly random cellular milieu however ratios are important, for example, the ratio of adenosine triphosphate to adenosine monophosphate, or oxidized to reduced glutathione. Health status is determined by simple ratios, such as the waist hip ratio, or ratio of fat mass to lean mass. Some nutrient ratios exist and remain controversial such as the omega-6/omega-3 fatty acid ratio and the sodium/potassium ratio. Therefore, examining ratios of micronutrients may convey more information about how diet and health outcomes are related. Summarized micronutrient intake data, from food only, from the National Health and Nutrition Examination Survey, were used to generate initial ratios. Overall, in this preliminary analysis dietary ratios of micronutrients showed some differences between intakes and recommendations. Principles outlined here could be used in nutritional epidemiology and in basic nutritional research, rather than focusing on individual nutrient intakes. This paper presents the concept of micronutrient ratios to encourage change in the way nutrients are regarded.

Effects of shelter and enrichment on the ecology and nutrient cycling of microbial communities of subtidal carbonate sediments.

Science.gov (United States)

Forehead, Hugh I; Kendrick, Gary A; Thompson, Peter A

2012-04-01

The interactions between physical disturbances and biogeochemical cycling are fundamental to ecology. The benthic microbial community controls the major pathway of nutrient recycling in most shallow-water ecosystems. This community is strongly influenced by physical forcing and nutrient inputs. Our study tests the hypotheses that benthic microbial communities respond to shelter and enrichment with (1) increased biomass, (2) change in community composition and (3) increased uptake of inorganic nutrients from the water column. Replicate in situ plots were sheltered from physical disturbance and enriched with inorganic nutrients or left without additional nutrients. At t(0) and after 10 days, sediment-water fluxes of nutrients, O(2) and N(2) , were measured, the community was characterized with biomarkers. Autochthonous benthic microalgal (BMA) biomass increased 30% with shelter and a natural fivefold increase in nutrient concentration; biomass did not increase with greater enrichment. Diatoms remained the dominant taxon of BMA, suggesting that the sediments were not N or Si limited. Bacteria and other heterotrophic organisms increased with enrichment and shelter. Daily exchanges of inorganic nutrients between sediments and the water column did not change in response to shelter or nutrient enrichment. In these sediments, physical disturbance, perhaps in conjunction with nutrient enrichment, was the primary determinant of microbial biomass. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Thinking outside of the Lake: Can controls on nutrient inputs into Lake Erie benefit stream conservation in its watershed?

Science.gov (United States)

Investment in agricultural conservation practices (CPs) to address Lake Erie's re-eutrophication may offer benefits that extend beyond the lake, such as improved habitat conditions for fish communities throughout the watershed. If such conditions are not explicitly considered in Lake Erie nutrient ...

Mapping of trophic states based on nutrients concentration and phytoplankton abundance in Jatibarang Reservoir

Science.gov (United States)

Rudiyanti, Siti; Anggoro, Sutrisno; Rahman, Arif

2018-02-01

Jatibarang Reservoir is one of the Indonesian Reservoirs, which used for human activities such as tourism and agriculture. These activities will provide input of organic matter and nutrients into the water. These materials will impact water quality and eutrophication process. Eutrophication is the water enrichment by nutrients, especially nitrogen and phosphorus which can promote the growth of phytoplankton. Some indicators of eutrophication are increasing nutrients, trophic states, and change of phytoplankton composition. The relationship between water quality and phytoplankton community can be used as an indicator of trophic states in Jatibarang Reservoir. The aim of this study was to analyze the effect of nutrients concentration and phytoplankton abundance to the trophic states and mapping trophic states based on nutrients concentration and phytoplankton in Jatibarang Reservoir. This study was conducted in June and July 2017 at 9 stations around Jatibarang Reservoir. The results showed that average concentration of nitrate, phosphate, and chlorophyll-a in Jatibarang Reservoir was 0.69 mg/L, 0.27 mg/L, and 1.66 mg/m3, respectively. The phytoplankton abundance ranged 16-62,200 cells/L, consists of 21 genera of four classes, i.e. Chlorophyceae, Cyanophyceae, Bacillariophyceae, and Dinophyceae. Cyanophyceae was a dominant phytoplankton group based on the composition of abundance (>80%). High nutrient concentrations and phytoplankton dominated by Anabaena (Cyanophyceae) which indicated that the waters in Jatibarang Reservoir were eutrophic.

Coherent single-photon absorption by single emitters coupled to one-dimensional nanophotonic waveguides

Energy Technology Data Exchange (ETDEWEB)

Chen Yuntian; Wubs, Martijn; Moerk, Jesper [DTU Fotonik, Department of Photonics Engineering, Oersteds Plads, DK-2800 Kgs Lyngby (Denmark); Koenderink, A Femius, E-mail: yche@fotonik.dtu.dk [Center for Nanophotonics, FOM Institute for Atomic and Molecular Physics (AMOLF), Science Park 104, 1098 XG Amsterdam (Netherlands)

2011-10-15

We study the dynamics of single-photon absorption by a single emitter coupled to a one-dimensional waveguide that simultaneously provides channels for spontaneous emission (SE) decay and a channel for the input photon. We have developed a time-dependent theory that allows us to specify any input single-photon wavepacket guided by the waveguide as the initial condition, and calculate the excitation probability of the emitter, as well as the time evolution of the transmitted and reflected fields. For single-photon wavepackets with a Gaussian spectrum and temporal shape, we obtain analytical solutions for the dynamics of absorption, with maximum atomic excitation {approx}40%. We furthermore propose a terminated waveguide to aid the single-photon absorption. We found that for an emitter placed at an optimal distance from the termination, the maximum atomic excitation due to an incident single-photon wavepacket can exceed 70%. This high value is a direct consequence of the high SE {beta}-factor for emission into the waveguide. Finally, we have also explored whether waveguide dispersion could aid single-photon absorption by pulse shaping. For a Gaussian input wavepacket, we found that the absorption efficiency can be improved by a further 4% by engineering the dispersion. Efficient single-photon absorption by a single emitter has potential applications in quantum communication and quantum computation. (paper)

High-order sliding mode observer for fractional commensurate linear systems with unknown input

KAUST Repository

Belkhatir, Zehor; Laleg-Kirati, Taous-Meriem

2017-01-01

In this paper, a high-order sliding mode observer (HOSMO) is proposed for the joint estimation of the pseudo-state and the unknown input of fractional commensurate linear systems with single unknown input and a single output. The convergence of the proposed observer is proved using a Lyapunov-based approach. In addition, an enhanced variant of the proposed fractional-HOSMO is introduced to avoid the peaking phenomenon and thus to improve the estimation results in the transient phase. Simulation results are provided to illustrate the performance of the proposed fractional observer in both noise-free and noisy cases. The effect of the observer’s gains on the estimated pseudo-state and unknown input is also discussed.

High-order sliding mode observer for fractional commensurate linear systems with unknown input

KAUST Repository

Belkhatir, Zehor

2017-05-20

In this paper, a high-order sliding mode observer (HOSMO) is proposed for the joint estimation of the pseudo-state and the unknown input of fractional commensurate linear systems with single unknown input and a single output. The convergence of the proposed observer is proved using a Lyapunov-based approach. In addition, an enhanced variant of the proposed fractional-HOSMO is introduced to avoid the peaking phenomenon and thus to improve the estimation results in the transient phase. Simulation results are provided to illustrate the performance of the proposed fractional observer in both noise-free and noisy cases. The effect of the observer’s gains on the estimated pseudo-state and unknown input is also discussed.

Opportunities to enhance and interpret nutrient fluxes and imbalances in animal production systems by use of stable isotopes

International Nuclear Information System (INIS)

Jarvis, S.C.

2002-01-01

Full text: The flows and transfers of nutrients within agricultural systems are complex and the presence of livestock increases the complexity. Few, if any, systems are in equilibrium with respect to nutrients inputs and outputs and all are 'leaky' to some extent or other: the presence of animals inevitably increases the opportunity for inefficiency. Whilst there is still much need to enhance nutrient use in many parts of the world in order to promote crop/food production particularly in resource-poor environments, there has been considerable recent research which re- examine nutrient behaviour because of pollution effects. Understanding nutrients fluxes and budgets/balances of inputs and outputs within a system and its component parts, provides the means to assess (i) current status, (ii) extent of losses and (iii) potential options for change to reduce losses, increase nutrient use efficiency and sustain or enhance production at minimum cost. Increasingly, nutrient accounting is being used at field, farm and national scales to aid decision making and planning. To do this effectively, requires that the sources and transfers of nutrients to, from and within the system be known. The paper discusses the way in which systems and farm gate balances can be used to promote efficiency of nutrient use in relation to required production levels and to optimise (i) investment in purchased nutrients, (ii) opportunities to capitalise on internal recycling and (iii) other farming activities which influence nutrient balance, surplus and loss. A major challenge for the future will be to balance the on- and off-farm needs of supplying and utilising nutrients in order to maintain long-term sustainability of farming systems, food production and rural resources. The paper concentrates on aspects of N in livestock systems as this provides one of the main opportunities to increase effectiveness of nutrient use in agriculture throughout the world with the aim of demonstrating some of the

Analysis of Input and Output Ripples of PWM AC Choppers

Directory of Open Access Journals (Sweden)

Pekik Argo Dahono

2008-11-01

Full Text Available This paper presents an analysis of input and output ripples of PWM AC choppers. Expressions of input and output current and voltage ripples of single-phase PWM AC choppers are first derived. The derived expressions are then extended to three-phase PWM AC choppers. As input current and output voltage ripples specification alone cannot be used to determine the unique values of inductance and capacitance of the LC filters, an additional criterion based on the minimum reactive power is proposed. Experimental results are included in this paper to show the validity of the proposed analysis method.

Responses of plant nutrient resorption to phosphorus addition in freshwater marsh of Northeast China

Science.gov (United States)

Mao, Rong; Zeng, De-Hui; Zhang, Xin-Hou; Song, Chang-Chun

2015-01-01

Anthropogenic activities have increased phosphorus (P) inputs to most aquatic and terrestrial ecosystems. However, the relationship between plant nutrient resorption and P availability is still unclear, and much less is known about the underlying mechanisms. Here, we used a multi-level P addition experiment (0, 1.2, 4.8, and 9.6 g P m−2 year−1) to assess the effect of P enrichment on nutrient resorption at plant organ, species, and community levels in a freshwater marsh of Northeast China. The response of nutrient resorption to P addition generally did not vary with addition rates. Moreover, nutrient resorption exhibited similar responses to P addition across the three hierarchical levels. Specifically, P addition decreased nitrogen (N) resorption proficiency, P resorption efficiency and proficiency, but did not impact N resorption efficiency. In addition, P resorption efficiency and proficiency were linearly related to the ratio of inorganic P to organic P and organic P fraction in mature plant organs, respectively. Our findings suggest that the allocation pattern of plant P between inorganic and organic P fractions is an underlying mechanism controlling P resorption processes, and that P enrichment could strongly influence plant-mediated biogeochemical cycles through altered nutrient resorption in the freshwater wetlands of Northeast China. PMID:25631373

Determination of the algal growth-limiting nutrients in strip mine ponds

International Nuclear Information System (INIS)

Bucknavage, M.J.; Aharrah, E.C.

1984-01-01

Using both a test organism, Ankistrodesmus falcatus, and natural phytoplankton, the Printz Algal Assay Bottle Test was used to determine the algal growth limiting nutrients in two strip mine ponds. Nitrogen, phosphorus, and iron were investigated, singly and in combination, as possible limiting nutrients. A synthetic chelator, Na 2 EDTA, was also used in the assay to test for the presence of metal toxicants and/or trace metal limitation. Because bacteria have a major influence on water chemistry, a separate assay incorporating the natural bacteria population was performed. In both ponds, assay results using test alga indicate phosphorus to be the primary limiting nutrient and nitrogen as a secondary factor. The presence of EDTA in combination with phosphate containing treatment promoted a higher algal concentration in both ponds. Iron was determined to be a secondary limiting nutrient in only one of the ponds. Natural phytoplankton of the two ponds responded in a similar manner to nutrient increases. Only one pond had the same results produced by both assays. Nutrient availability was influenced by the presence of bacteria in one pond but not in the other

Seasonal variation in physicochemical properties of coastal waters of Kalpakkam, east coast of India with special emphasis on nutrients.

Science.gov (United States)

Satpathy, K K; Mohanty, A K; Natesan, U; Prasad, M V R; Sarkar, S K

2010-05-01

A study pertaining to the seasonal variation in physicochemical properties of the coastal waters was carried out at Kalpakkam coast for a period of 1 year (February 2006 to January 2007). It revealed that the coastal water was significantly influenced by freshwater input during North East (NE) monsoon and post-monsoon periods. Concentration of all the nutrients and dissolved oxygen (DO) was relatively high during the NE monsoon, whereas, salinity and chlorophyll-a (chl-a) were at their minimum level during this period. Phytoplankton production peak was observed in summer during which a typical marine condition prevailed. The present observed values of nitrate, phosphate, silicate, and turbidity are significantly high (five to ten times) compared to that of the pre-Tsunami period from this coast. Relatively low DO and chl-a concentration was noticed during the post-Tsunami period. A notable feature of this study is that though nutrient concentration in the coastal waters during post-Tsunami period has increased significantly, turbidity, the most single dominating factor, was found to adversely affect the phytoplankton production during post-Tsunami period as reflected by relatively low chl-a concentration. Thus, the post-Tsunami period may result in a change in coastal biodiversity pattern concomitant with change in coastal water quality.

Carbon sequestration and nutrient reserves under differen t land use systems

Directory of Open Access Journals (Sweden)

Maria Ivanilda Aguiar

2014-02-01

Full Text Available This study evaluated the contribution of agroforestry (AFS and traditional systems to carbon sequestration and nutrient reserves in plants, litter and soil. The study was carried out in the semiarid region of Brazil in a long-term experiment on an experimental farm of the goat and sheep section of the Brazilian Agricultural Research Corporation (Embrapa. Two agroforestry systems were investigated: agrosilvopastoral (ASP and forest-pasture areas (SP as well as traditional agriculture management (TM, two areas left fallow after TM (six fallow years - F6 and nine fallow years - F9 and one area of preserved Caatinga vegetation (CAT. Soil, litter and plants were sampled from all areas and the contents of C, N, P, K, Ca and Mg per compartment determined. The AFS (ASP and SP had higher nutrient stocks than the traditional and intermediate stocks compared to the preserved Caatinga. In the ASP, a relevant part of the nutrients extracted by crops is returned to the system by constant inputs of litter, weeding of herbaceous vegetation and cutting of the legume crops. After fallow periods of six and nine years, carbon and nutrient stocks in the compartments soil, litter and herbaceous plants were similar to those of the preserved Caatinga (CAT, but still lower than under natural conditions in the woody vegetation.

Improved Hypoxia Modeling for Nutrient Control Decisions in the Gulf of Mexico

Science.gov (United States)

Habib, Shahid; Pickering, Ken; Tzortziou, Maria; Maninio, Antonio; Policelli, Fritz; Stehr, Jeff

2011-01-01

The Gulf of Mexico Modeling Framework is a suite of coupled models linking the deposition and transport of sediment and nutrients to subsequent bio-geo chemical processes and the resulting effect on concentrations of dissolved oxygen in the coastal waters of Louisiana and Texas. Here, we examine the potential benefits of using multiple NASA remote sensing data products within this Modeling Framework for increasing the accuracy of the models and their utility for nutrient control decisions in the Gulf of Mexico. Our approach is divided into three components: evaluation and improvement of (a) the precipitation input data (b) atmospheric constituent concentrations in EPA's air quality/deposition model and (c) the calculation of algal biomass, organic carbon and suspended solids within the water quality/eutrophication models of the framework.

Plasticity of the cis-regulatory input function of a gene.

Directory of Open Access Journals (Sweden)

Avraham E Mayo

2006-04-01

Full Text Available The transcription rate of a gene is often controlled by several regulators that bind specific sites in the gene's cis-regulatory region. The combined effect of these regulators is described by a cis-regulatory input function. What determines the form of an input function, and how variable is it with respect to mutations? To address this, we employ the well-characterized lac operon of Escherichia coli, which has an elaborate input function, intermediate between Boolean AND-gate and OR-gate logic. We mapped in detail the input function of 12 variants of the lac promoter, each with different point mutations in the regulator binding sites, by means of accurate expression measurements from living cells. We find that even a few mutations can significantly change the input function, resulting in functions that resemble Pure AND gates, OR gates, or single-input switches. Other types of gates were not found. The variant input functions can be described in a unified manner by a mathematical model. The model also lets us predict which functions cannot be reached by point mutations. The input function that we studied thus appears to be plastic, in the sense that many of the mutations do not ruin the regulation completely but rather result in new ways to integrate the inputs.

Seasonal Variation and Sources of Dissolved Nutrients in the Yellow River, China

Directory of Open Access Journals (Sweden)

Yao Gong

2015-08-01

Full Text Available The rapid growth of the economy in China has caused dramatic growth in the industrial and agricultural development in the Yellow River (YR watershed. The hydrology of the YR has changed dramatically due to the climate changes and water management practices, which have resulted in a great variation in the fluxes of riverine nutrients carried by the YR. To study these changes dissolved nutrients in the YR were measured monthly at Lijin station in the downstream region of the YR from 2002 to 2004. This study provides detailed information on the nutrient status for the relevant studies in the lower YR and the Bohai Sea. The YR was enriched in nitrate (average 314 μmol·L−1 with a lower concentration of dissolved silicate (average 131 μmol·L−1 and relatively low dissolved phosphate (average 0.35 μmol·L−1. Nutrient concentrations exhibited substantial seasonal and yearly variations. The annual fluxes of dissolved inorganic nitrogen, phosphate, and silicate in 2004 were 5.3, 2.5, and 4.2 times those in 2002, respectively, primarily due to the increase in river discharge. The relative contributions of nutrient inputs to nitrogen in the YR were: wastewater > fertilizer > atmospheric deposition > soil; while to phosphorus were: wastewater > fertilizer > soil > atmospheric deposition. The ratios of N, P and Si suggest that the YR at Lijin is strongly P-limited with respect to potential phytoplankton growth.

Linking environmental nutrient enrichment and disease emergence in humans and wildlife

Science.gov (United States)

Johnson, Pieter T. J.; Townsend, Alan R.; Cleveland, Cory C.; Glibert, Patricia M.; Howarth, Robert W.; McKenzie, Valerie J.; Rejmankova, Eliska; Ward, Mary H.

2009-01-01

Worldwide increases in the numbers of human and wildlife diseases present ecologists with the challenge of understanding how large-scale environmental changes affect host-parasite interactions. One of the most profound changes to Earth’s ecosystems is the alteration of global nutrient cycles, including those of phosphorus (P) and especially nitrogen (N). Alongside the obvious direct benefits of nutrient application for food production, growing evidence suggests that anthropogenic inputs of N and P can indirectly affect the abundance of infectious and noninfectious pathogens, sometimes leading to epidemic conditions. However, the mechanisms underpinning observed correlations, and how such patterns vary with disease type, have long remained conjectural. Here, we discuss recent experimental advances in this area to critically evaluate the relationship between environmental nutrient enrichment and disease. Given the inter-related nature of human and wildlife disease emergence, we include a broad range of human and wildlife examples from terrestrial, marine and freshwater ecosystems. We examine the consequences of nutrient pollution on directly transmitted, vector-borne, complex life cycle, and noninfectious pathogens, including West Nile virus, malaria, harmful algal blooms, coral reef diseases and amphibian malformations. Our synthetic examination suggests that the effects of environmental nutrient enrichment on disease are complex and multifaceted, varying with the type of pathogen, host species and condition, attributes of the ecosystem and the degree of enrichment; some pathogens increase in abundance whereas others decline or disappear. Nevertheless, available evidence indicates that ecological changes associated with nutrient enrichment often exacerbate infection and disease caused by generalist parasites with direct or simple life cycles. Observed mechanisms include changes in host/vector density, host distribution, infection resistance, pathogen virulence or

Long-term trends in nutrient budgets of the western Dutch Wadden Sea (1976-2012)

Science.gov (United States)

Jung, A. S.; Brinkman, A. G.; Folmer, E. O.; Herman, P. M. J.; van der Veer, H. W.; Philippart, C. J. M.

2017-09-01

Long-term field observations of nitrogen [N] and phosphorus [P] concentrations were used to construct nutrient budgets for the western Dutch Wadden Sea between 1976 and 2012. Nutrients come into the western Dutch Wadden Sea via river runoff, through exchange with the coastal zone of the North Sea, neighbouring tidal basins and through atmospheric deposition (for N). The highest concentrations in phosphorus and nitrogen were observed in the mid-1980s. Improved phosphorus removal at waste water treatment plants, management of fertilization in agriculture and removal of phosphates from detergents led to reduced riverine nutrient inputs and, consequently, reduced nutrient concentrations in the Wadden Sea. The budgets suggest that the period of the initial net import of phosphorus and nitrogen switched to a net export in 1981 for nitrogen and in 1992 for phosphorus. Such different behaviour in nutrient budgets during the rise and fall of external nutrient concentrations may be the result of different sediment-water exchange dynamics for P and N. It is hypothesized that during the period of increasing eutrophication (1976-1981) P, and to a lesser degree N, were stored in sediments as organic and inorganic nutrients. In the following period (1981-1992) external nutrient concentrations (especially in the North Sea) decreased, but P concentrations in the Wadden Sea remained high due to prolonged sediment release, whilst denitrification removed substantial amounts of N. From 1992 onwards, P and N budgets were closed by net loss, most probably because P stores were then depleted and denitrification continued. Under the present conditions (lower rates of sediment import and depleted P stores), nutrient concentrations in this area are expected to be more strongly influenced by wind-driven exchange with the North Sea and precipitation-driven discharge from Lake IJssel. This implies that the consequences of climate change will be more important, than during the 1970s and 1980s.

Nutrient fluxes in litterfall of a secondary successional alluvial rain forest in Southern Brazil

Directory of Open Access Journals (Sweden)

Maurício Bergamini Scheer

2011-12-01

Full Text Available During forest succession, litterfall nutrient fluxes increase significantly. The higher inputs of organic matter and nutrients through litterfall affects positively soil fertility and the species composition, which are essential components in forest restoration and management programs. In the present study, the input of nutrients to the forest soil via litterfall components was estimated for two sites of different development stages, in an early successional alluvial rain forest in Brazil. Litterfall returned to the soil, in kg/ha, ca. 93 N, 79 Ca, 24 K, 15 Mg, 6 P, 1.7 Mn, 0.94 Fe, 0.18 Zn, 0.09 Cu and 11.2 Al, in the site where trees were more abundant and had higher values of basal area. In the other area, where trees where less abundant and values of basal area were comparatively low, litterfall returned Durante la sucesión secundaria forestal, el flujo de nutrientes en la hojarasca se incrementa significativamente. Los altos ingresos de materia orgánica y nutrientes a través de la hojarasca afecta positivamente la fertilidad del suelo y la composición de especies, las cuales son componentes esenciales para programas de restauración forestal y de manejo. En el presente estudio, el ingreso de nutrientes a través de la hojarasca y sus componentes fueron estimados para dos sitios de una selva lluviosa atlántica aluvial en sucesión temprana. La cantidad anual de elementos que ingresan al suelo desde la vegetación más desarrollada (sitios con alta área basal y abundancia de árboles fueron (en kg/ha: 93 N, 79 Ca, 24 K, 15 Mg, 6 P, 1.7 Mn, 0.94 Fe, 0.18 Zn, 0.09 Cu y 11.2 Al. Menos de la mitad de esas cantidades fueron aportadas por la vegetación menos desarrollada, excepto para el Al. La cantidad de Al aportada a este sitio fue similar a la contribución de la vegetación más desarrollada, debido a la contribución de: Tibouchina pulchra (82% de todo el Al aportado. La eficiencia en el uso de nutrientes de la hojarasca

Estimating the Cross-Shelf Export of Riverine Materials: Part 2. Estimates of Global Freshwater and Nutrient Export

Science.gov (United States)

Izett, Jonathan G.; Fennel, Katja

2018-02-01

Rivers deliver large amounts of fresh water, nutrients, and other terrestrially derived materials to the coastal ocean. Where inputs accumulate on the shelf, harmful effects such as hypoxia and eutrophication can result. In contrast, where export to the open ocean is efficient riverine inputs contribute to global biogeochemical budgets. Assessing the fate of riverine inputs is difficult on a global scale. Global ocean models are generally too coarse to resolve the relatively small scale features of river plumes. High-resolution regional models have been developed for individual river plume systems, but it is impractical to apply this approach globally to all rivers. Recently, generalized parameterizations have been proposed to estimate the export of riverine fresh water to the open ocean (Izett & Fennel, 2018, https://doi.org/10.1002/2017GB005667; Sharples et al., 2017, https://doi.org/10.1002/2016GB005483). Here the relationships of Izett and Fennel, https://doi.org/10.1002/2017GB005667 are used to derive global estimates of open-ocean export of fresh water and dissolved inorganic silicate, dissolved organic carbon, and dissolved organic and inorganic phosphorus and nitrogen. We estimate that only 15-53% of riverine fresh water reaches the open ocean directly in river plumes; nutrient export is even less efficient because of processing on continental shelves. Due to geographic differences in riverine nutrient delivery, dissolved silicate is the most efficiently exported to the open ocean (7-56.7%), while dissolved inorganic nitrogen is the least efficiently exported (2.8-44.3%). These results are consistent with previous estimates and provide a simple way to parameterize export to the open ocean in global models.

Effect of multi-nutrient complex fertilizers on growth and tuber yield of very early potato (Solanum tuberosum L. cultivars

Directory of Open Access Journals (Sweden)

Wanda Wadas

2013-10-01

Full Text Available The aim of the study was to compare the effect of multi-nutrient complex fertilizers (HydroComplex, Nitrophoska Blue Special and Viking 13 from the nitrophoska group, and Polimag S from the amophoska group and single-nutrient fertilizers on the growth and tuber yield of very early potato cultivars (‘Aster’, ‘Fresco’, ‘Gloria’. The field experiment was carried out on podzolic soil in mid-eastern Poland during 2005–2007. The study showed a greater beneficial effect of HydroComplex and Nitrophoska Blue Special on the growth of very early potato cultivars than that of Viking 13 and Polimag S. The application of HydroComplex and Nitrophoska Blue Special resulted in greater above-ground plant biomass and assimilation leaf area compared with single-nutrient fertilizers; the leaf area index (LAI was higher by 0.28 and 0.32, respectively. The differences were smaller and not statistically confirmed with the use of Polimag S and Viking 13. When the multi-nutrient complex fertilizers were applied, leaf weight ratio (LWR, leaf area ratio (LAR and specific leaf area (SLA were similar to the single-nutrient fertilizers. Of the multi-nutrient complex fertilizers, only Nitrophoska Blue Special resulted in higher tuber yield, on average by 2.40 t × ha-1, compared with the single-nutrient fertilizers. The studied cultivars showed a similar response to applied fertilizers. LAI for ‘Gloria’ was higher than for ‘Aster’ and ‘Fresco’, with smaller LAR found in ‘Gloria’. LWR for ‘Fresco’ was smaller than for ‘Aster’ and ‘Gloria’, with higher SLA found in ‘Fresco’. The tuber yield of ‘Aster” (24.04 t × ha-1 was higher on average by 3 t × ha-1 than for ‘Fresco’ and ‘Gloria’.

GESAMP Working Group 38, The Atmospheric Input of Chemicals to the Ocean

Science.gov (United States)

Duce, Robert; Liss, Peter

2014-05-01

There is growing recognition of the impact of the atmospheric input of both natural and anthropogenic substances on ocean chemistry, biology, and biogeochemistry as well as climate. These inputs are closely related to a number of important global change issues. For example, the increasing input of anthropogenic nitrogen species from the atmosphere to much of the ocean may cause a low level fertilization that could result in an increase in marine 'new' productivity of up to ~3% and thus impact carbon drawdown from the atmosphere. Similarly, much of the oceanic iron, which is a limiting nutrient in significant areas of the ocean, originates from the atmospheric input of minerals as a result of the long-range transport of mineral dust from continental regions. The increased supply of soluble phosphorus from atmospheric anthropogenic sources (through large-scale use of fertilizers) may also have a significant impact on surface-ocean biogeochemistry, but estimates of any effects are highly uncertain. There have been few assessments of the atmospheric inputs of sulfur and nitrogen oxides to the ocean and their impact on the rates of ocean acidification. These inputs may be particularly critical in heavily trafficked shipping lanes and in ocean regions proximate to highly industrialized land areas. Other atmospheric substances may also have an impact on the ocean, in particular lead, cadmium, and POPs. To address these and related issues the United Nations Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) initiated Working Group 38, The Atmospheric Input of Chemicals to the Ocean, in 2008. This Working Group has had four meetings. To date four peer reviewed papers have been produced from this effort, with a least eight others in the process of being written or published. This paper will discuss some of the results of the Working Group's deliberations and its plans for possible future work.

Stream Nitrogen Inputs Reflect Groundwater Across a Snowmelt-Dominated Montane to Urban Watershed.

Science.gov (United States)

Hall, Steven J; Weintraub, Samantha R; Eiriksson, David; Brooks, Paul D; Baker, Michelle A; Bowen, Gabriel J; Bowling, David R

2016-02-02

Snowmelt dominates the hydrograph of many temperate montane streams, yet little work has characterized how streamwater sources and nitrogen (N) dynamics vary across wildland to urban land use gradients in these watersheds. Across a third-order catchment in Salt Lake City, Utah, we asked where and when groundwater vs shallow surface water inputs controlled stream discharge and N dynamics. Stream water isotopes (δ(2)H and δ(18)O) reflected a consistent snowmelt water source during baseflow. Near-chemostatic relationships between conservative ions and discharge implied that groundwater dominated discharge year-round across the montane and urban sites, challenging the conceptual emphasis on direct stormwater inputs to urban streams. Stream and groundwater NO3(-) concentrations remained consistently low during snowmelt and baseflow in most montane and urban stream reaches, indicating effective subsurface N retention or denitrification and minimal impact of fertilizer or deposition N sources. Rather, NO3(-) concentrations increased 50-fold following urban groundwater inputs, showing that subsurface flow paths potentially impact nutrient loading more than surficial land use. Isotopic composition of H2O and NO3(-) suggested that snowmelt-derived urban groundwater intercepted NO3(-) from leaking sewers. Sewer maintenance could potentially mitigate hotspots of stream N inputs at mountain/valley transitions, which have been largely overlooked in semiarid urban ecosystems.

A Review of Nutrient Management Studies Involving Finger Millet in the Semi-Arid Tropics of Asia and Africa

Directory of Open Access Journals (Sweden)

Malinda S. Thilakarathna

2015-06-01

Full Text Available Finger millet (Eleusine coracana (L. Gaertn is a staple food crop grown by subsistence farmers in the semi-arid tropics of South Asia and Africa. It remains highly valued by traditional farmers as it is nutritious, drought tolerant, short duration, and requires low inputs. Its continued propagation may help vulnerable farmers mitigate climate change. Unfortunately, the land area cultivated with this crop has decreased, displaced by maize and rice. Reversing this trend will involve achieving higher yields, including through improvements in crop nutrition. The objective of this paper is to comprehensively review the literature concerning yield responses of finger millet to inorganic fertilizers (macronutrients and micronutrients, farmyard manure (FYM, green manures, organic by-products, and biofertilizers. The review also describes the impact of these inputs on soils, as well as the impact of diverse cropping systems and finger millet varieties, on nutrient responses. The review critically evaluates the benefits and challenges associated with integrated nutrient management, appreciating that most finger millet farmers are economically poor and primarily use farmyard manure. We conclude by identifying research gaps related to nutrient management in finger millet, and provide recommendations to increase the yield and sustainability of this crop as a guide for subsistence farmers.

Cancer: a single disease with a multitude of manifestions?

Directory of Open Access Journals (Sweden)

Grandics Peter

2003-01-01

Full Text Available Abstract The relationships of critical nutrients such as plant phenolics, vitamins, minerals and lipids are considered with respect to the incidence of a variety of cancers, and analyzed in terms of how these nutrient deficiencies alter immune function, DNA integrity and cell proliferation. With a significant correlation found between cancer and these nutrient deficiencies, the hypothesis is presented here that nutrition could provide a unifying perception of cancer and recast it as a single disease. This further suggests that a coordinated administration of specific, critical nutrients to cancer patients could lead to the reversal of the disease. It is also proposed that the concurrent presence of a variety of nutritional deficiencies in cancer patients requires a multilevel, systemic approach to this disease as opposed to the single active therapeutic agent approach that is the cornerstone of contemporary research and pharmacology.

Impact of wildfire on stream nutrient chemistry and ecosystem metabolism in boreal forest catchments of interior Alaska

Science.gov (United States)

Emma F. Betts; Jeremy B. Jones

2009-01-01

With climatic warming, wildfire occurrence is increasing in the boreal forest of interior Alaska. Loss of catchment vegetation during fire can impact streams directly through altered solute and debris inputs and changed light and temperature regimes. Over longer time scales, fire can accelerate permafrost degradation, altering catchment hydrology and stream nutrient...

Dissolved organic matter and lake metabolism: Biogeochemistry and controls of nutrient flux dynamics to fresh waters. Technical progress report, January 1, 1990--December 31, 1991

Energy Technology Data Exchange (ETDEWEB)

Wetzel, R.G.

1992-12-31

The land-water interface region consists of two major components: the wetland, and the down-gradient adjacent littoral floating-leaved and submersed, macrophyte communities. Because of the importance of very high production and nutrient turnover of attached microbiota, a major emphasis of this investigation was placed upon these biota and their metabolic capacities for assimilation and release of organic compounds and nutrient retention and cycling. Examination of the capacities of wetland littoral communities to regulate fluxes of nutrients and organic compounds often has been limited to input-output analyses. These input-output data are an integral part of these investigations, but most of the research effort concentrated on the biotic and metabolic mechanisms that control fluxes and retention capacities and their effects upon biota in the down-gradient waters. The important regulatory capacities of dissolved organic compounds on enzyme reactivity was examined experimentally and coupled to the wetland-littoral organic carbon flux budgets.

Increasing inhibitory input increases neuronal firing rate: why and when? Diffusion process cases

Energy Technology Data Exchange (ETDEWEB)

Feng Jianfeng [COGS, Sussex University (United Kingdom)]. E-mail: jf218@cam.ac.uk; Wei Gang [Department of Mathematics, Hong Kong Baptist University, Hong Kong (China)]. E-mail gwei@math.hkbu.edu.hk

2001-09-21

Increasing inhibitory input to single neuronal models, such as the FitzHugh-Nagumo model and the Hodgkin-Huxley model, can sometimes increase their firing rates, a phenomenon which we term inhibition-boosted firing (IBF). Here we consider neuronal models with diffusion approximation inputs, i.e. they share the identical first- and second-order statistics of the corresponding Poisson process inputs. Using the integrate-and-fire model and the IF-FHN model, we explore theoretically how and when IBF can happen. For both models, it is shown that there is a critical input frequency at which the efferent firing rate is identical when the neuron receives purely excitatory inputs or exactly balanced inhibitory and excitatory inputs. When the input frequency is lower than the critical frequency, IBF occurs. (author)

Estimated anthropogenic nitrogen and phosphorus inputs to the land surface of the conterminous United States--1992, 1997, and 2002

Science.gov (United States)

Sprague, Lori A.; Gronberg, Jo Ann M.

2013-01-01

Anthropogenic inputs of nitrogen and phosphorus to each county in the conterminous United States and to the watersheds of 495 surface-water sites studied as part of the U.S. Geological Survey National Water-Quality Assessment Program were quantified for the years 1992, 1997, and 2002. Estimates of inputs of nitrogen and phosphorus from biological fixation by crops (for nitrogen only), human consumption, crop production for human consumption, animal production for human consumption, animal consumption, and crop production for animal consumption for each county are provided in a tabular dataset. These county-level estimates were allocated to the watersheds of the surface-water sites to estimate watershed-level inputs from the same sources; these estimates also are provided in a tabular dataset, together with calculated estimates of net import of food and net import of feed and previously published estimates of inputs from atmospheric deposition, fertilizer, and recoverable manure. The previously published inputs are provided for each watershed so that final estimates of total anthropogenic nutrient inputs could be calculated. Estimates of total anthropogenic inputs are presented together with previously published estimates of riverine loads of total nitrogen and total phosphorus for reference.

The Nutrient Density of Snacks: A Comparison of Nutrient Profiles of Popular Snack Foods Using the Nutrient-Rich Foods Index.

Science.gov (United States)

Hess, Julie; Rao, Goutham; Slavin, Joanne

2017-01-01

Background: Although Americans receive almost a quarter of their daily energy from snacks, snacking remains a poorly defined and understood eating occasion. However, there is little dietary guidance about choosing snacks. Families, clinicians, and researchers need a comprehensive approach to assessing their nutritional value. Objective: To quantify and compare the nutrient density of commonly consumed snacks by their overall nutrient profiles using the Nutrient-Rich Foods (NRF) Index 10.3. Methods: NRF Index scores were calculated for the top 3 selling products (based on 2014 market research data) in different snack categories. These NRF scores were averaged to provide an overall nutrient-density score for each category. Results: Based on NRF scores, yogurt (55.3), milk (52.5), and fruit (30.1) emerged as the most nutrient-dense snacks. Ice cream (-4.4), pies and cakes (-11.1), and carbonated soft drinks (-17.2) emerged as the most nutrient-poor snacks. Conclusions: The NRF Index is a useful tool for assessing the overall nutritional value of snacks based on nutrients to limit and nutrients to encourage.

Biochar and manure affect calcareous soil and corn silage nutrient concentrations and uptake.

Science.gov (United States)

Lentz, R D; Ippolito, J A

2012-01-01

Carbon-rich biochar derived from the pyrolysis of biomass can sequester atmospheric CO, mitigate climate change, and potentially increase crop productivity. However, research is needed to confirm the suitability and sustainability of biochar application to different soils. To an irrigated calcareous soil, we applied stockpiled dairy manure (42 Mg ha dry wt) and hardwood-derived biochar (22.4 Mg ha), singly and in combination with manure, along with a control, yielding four treatments. Nitrogen fertilizer was applied when needed (based on preseason soil test N and crop requirements) in all plots and years, with N mineralized from added manure included in this determination. Available soil nutrients (NH-N; NO-N; Olsen P; and diethylenetriaminepentaacetic acid-extractable K, Mg, Na, Cu, Mn, Zn, and Fe), total C (TC), total N (TN), total organic C (TOC), and pH were evaluated annually, and silage corn nutrient concentration, yield, and uptake were measured over two growing seasons. Biochar treatment resulted in a 1.5-fold increase in available soil Mn and a 1.4-fold increase in TC and TOC, whereas manure produced a 1.2- to 1.7-fold increase in available nutrients (except Fe), compared with controls. In 2009 biochar increased corn silage B concentration but produced no yield increase; in 2010 biochar decreased corn silage TN (33%), S (7%) concentrations, and yield (36%) relative to controls. Manure produced a 1.3-fold increase in corn silage Cu, Mn, S, Mg, K, and TN concentrations and yield compared with the control in 2010. The combined biochar-manure effects were not synergistic except in the case of available soil Mn. In these calcareous soils, biochar did not alter pH or availability of P and cations, as is typically observed for acidic soils. If the second year results are representative, they suggest that biochar applications to calcareous soils may lead to reduced N availability, requiring additional soil N inputs to maintain yield targets. Copyright © by the

Growth performance and nutrient digestibility of broiler chickens fed ...

African Journals Online (AJOL)

Two hundred and seventy (270), day old chicks were used in a completely randomized design experimental layout to test the growth performance and nutrient digestibility of broiler chickens fed single phase diets containing natuzyme™ treated groundnut shell at 0, 5, 10, 15, 20 and 25 % inclusion levels. The treatments ...

Optimal control of LQR for discrete time-varying systems with input delays

Science.gov (United States)

Yin, Yue-Zhu; Yang, Zhong-Lian; Yin, Zhi-Xiang; Xu, Feng

2018-04-01

In this work, we consider the optimal control problem of linear quadratic regulation for discrete time-variant systems with single input and multiple input delays. An innovative and simple method to derive the optimal controller is given. The studied problem is first equivalently converted into a problem subject to a constraint condition. Last, with the established duality, the problem is transformed into a static mathematical optimisation problem without input delays. The optimal control input solution to minimise performance index function is derived by solving this optimisation problem with two methods. A numerical simulation example is carried out and its results show that our two approaches are both feasible and very effective.

The effectiveness of aided augmented input techniques for persons with developmental disabilities: a systematic review.

Science.gov (United States)

Allen, Anna A; Schlosser, Ralf W; Brock, Kristofer L; Shane, Howard C

2017-09-01

When working with individuals with little or no functional speech, clinicians often recommend that communication partners use the client's augmentative and alternative communication (AAC) device when speaking to the client. This is broadly known as "augmented input" and is thought to enhance the client's learning of language form and content. The purpose of this systematic review was to determine the effects of augmented input on communication outcomes in persons with developmental disabilities and persons with childhood apraxia of speech who use aided AAC. Nineteen studies met the inclusion criteria. Each included study was reviewed in terms of participant characteristics, terminology used, symbol format, augmented input characteristics, outcomes measured, effectiveness, and study quality. Results indicate that augmented input can improve single-word vocabulary skills and expression of multi-symbol utterances; however, comprehension beyond the single word level has not been explored. Additionally, it is difficult to form conclusions about the effect of augmented input on specific diagnostic populations. Directions for future research are posited.

Nematodes enhance plant growth and nutrient uptake under C and N-rich conditions

Science.gov (United States)

Gebremikael, Mesfin T.; Steel, Hanne; Buchan, David; Bert, Wim; de Neve, Stefaan

2016-09-01

The role of soil fauna in crucial ecosystem services such as nutrient cycling remains poorly quantified, mainly because of the overly reductionistic approach adopted in most experimental studies. Given that increasing nitrogen inputs in various ecosystems influence the structure and functioning of soil microbes and the activity of fauna, we aimed to quantify the role of the entire soil nematode community in nutrient mineralization in an experimental set-up emulating nutrient-rich field conditions and accounting for crucial interactions amongst the soil microbial communities and plants. To this end, we reconstructed a complex soil foodweb in mesocosms that comprised largely undisturbed native microflora and the entire nematode community added into defaunated soil, planted with Lolium perenne as a model plant, and amended with fresh grass-clover residues. We determined N and P availability and plant uptake, plant biomass and abundance and structure of the microbial and nematode communities during a three-month incubation. The presence of nematodes significantly increased plant biomass production (+9%), net N (+25%) and net P (+23%) availability compared to their absence, demonstrating that nematodes link below- and above-ground processes, primarily through increasing nutrient availability. The experimental set-up presented allows to realistically quantify the crucial ecosystem services provided by the soil biota.

Nutrient Status Assessment in Individuals and Populations for Healthy Aging-Statement from an Expert Workshop.

Science.gov (United States)

Péter, Szabolcs; Saris, Wim H M; Mathers, John C; Feskens, Edith; Schols, Annemie; Navis, Gerjan; Kuipers, Folkert; Weber, Peter; Eggersdorfer, Manfred

2015-12-16

A workshop organized by the University Medical Center Groningen addressed various current issues regarding nutrient status of individuals and populations, tools and strategies for its assessment, and opportunities to intervene. The importance of nutrient deficiencies and information on nutrient status for health has been illustrated, in particular for elderly and specific patient groups. The nutrient profile of individuals can be connected to phenotypes, like hypertension or obesity, as well as to socio-economic data. This approach provides information on the relationship between nutrition (nutrient intake and status) and health outcomes and, for instance, allows us to use the findings to communicate and advocate a healthy lifestyle. Nutrition is complex: a broader profile of nutrients should be considered rather than focusing solely on a single nutrient. Evaluating food patterns instead of intake of individual nutrients provides better insight into relationships between nutrition and health and disease. This approach would allow us to provide feedback to individuals about their status and ways to improve their nutritional habits. In addition, it would provide tools for scientists and health authorities to update and develop public health recommendations.

Design and implementation of an efficient single layer five input majority voter gate in quantum-dot cellular automata.

Science.gov (United States)

Bahar, Ali Newaz; Waheed, Sajjad

2016-01-01

The fundamental logical element of a quantum-dot cellular automata (QCA) circuit is majority voter gate (MV). The efficiency of a QCA circuit is depends on the efficiency of the MV. This paper presents an efficient single layer five-input majority voter gate (MV5). The structure of proposed MV5 is very simple and easy to implement in any logical circuit. This proposed MV5 reduce number of cells and use conventional QCA cells. However, using MV5 a multilayer 1-bit full-adder (FA) is designed. The functional accuracy of the proposed MV5 and FA are confirmed by QCADesigner a well-known QCA layout design and verification tools. Furthermore, the power dissipation of proposed circuits are estimated, which shows that those circuits dissipate extremely small amount of energy and suitable for reversible computing. The simulation outcomes demonstrate the superiority of the proposed circuit.

Numerical simulations of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay, Indonesia

International Nuclear Information System (INIS)

Wulp, Simon A. van der; Damar, Ario; Ladwig, Norbert; Hesse, Karl-J.

2016-01-01

The present application of numerical modelling techniques provides an overview of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay. A hydrological model simulated river discharges with a total of 90 to 377 m 3 s −1 entering Jakarta Bay. Daily total nitrogen and total phosphorus loads ranged from 40 to 174 tons and 14 to 60 tons, respectively. Flow model results indicate that nutrient gradients are subject to turbulent mixing by tides and advective transport through circulation driven by wind, barotropic and baroclinic pressure gradients. The bulk of nutrient loads originate from the Citarum and Cisadane rivers flowing through predominantly rural areas. Despite lower nutrient loads, river discharges from the urban area of Jakarta exhibit the highest impact of nutrient concentrations in the near shore area of Jakarta Bay and show that nutrient concentrations were not only regulated by nutrient loads but were strongly regulated by initial river concentrations and local flow characteristics. - Highlights: • Full overview of river discharges, nutrient flux and nutrient levels in Jakarta Bay • Important overview of nutrient flux from individual rivers • Simulations identify the principal drivers of water circulation and nutrient gradient. • Nutrient dispersion model includes the local effects of the Java Sea current system.

A dual porosity model of nutrient uptake by root hairs

KAUST Repository

Zygalakis, K. C.; Kirk, G. J. D.; Jones, D. L.; Wissuwa, M.; Roose, T.

2011-01-01

Summary: • The importance of root hairs in the uptake of sparingly soluble nutrients is understood qualitatively, but not quantitatively, and this limits efforts to breed plants tolerant of nutrient-deficient soils. • Here, we develop a mathematical model of nutrient uptake by root hairs allowing for hair geometry and the details of nutrient transport through soil, including diffusion within and between soil particles. We give illustrative results for phosphate uptake. • Compared with conventional 'single porosity' models, this 'dual porosity' model predicts greater root uptake because more nutrient is available by slow release from within soil particles. Also the effect of soil moisture is less important with the dual porosity model because the effective volume available for diffusion in the soil is larger, and the predicted effects of hair length and density are different. • Consistent with experimental observations, with the dual porosity model, increases in hair length give greater increases in uptake than increases in hair density per unit main root length. The effect of hair density is less in dry soil because the minimum concentration in solution for net influx is reached more rapidly. The effect of hair length is much less sensitive to soil moisture. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

A dual porosity model of nutrient uptake by root hairs

KAUST Repository

Zygalakis, K. C.

2011-08-09

Summary: • The importance of root hairs in the uptake of sparingly soluble nutrients is understood qualitatively, but not quantitatively, and this limits efforts to breed plants tolerant of nutrient-deficient soils. • Here, we develop a mathematical model of nutrient uptake by root hairs allowing for hair geometry and the details of nutrient transport through soil, including diffusion within and between soil particles. We give illustrative results for phosphate uptake. • Compared with conventional \\'single porosity\\' models, this \\'dual porosity\\' model predicts greater root uptake because more nutrient is available by slow release from within soil particles. Also the effect of soil moisture is less important with the dual porosity model because the effective volume available for diffusion in the soil is larger, and the predicted effects of hair length and density are different. • Consistent with experimental observations, with the dual porosity model, increases in hair length give greater increases in uptake than increases in hair density per unit main root length. The effect of hair density is less in dry soil because the minimum concentration in solution for net influx is reached more rapidly. The effect of hair length is much less sensitive to soil moisture. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

Input and language development in bilingually developing children.

Science.gov (United States)

Hoff, Erika; Core, Cynthia

2013-11-01

Language skills in young bilingual children are highly varied as a result of the variability in their language experiences, making it difficult for speech-language pathologists to differentiate language disorder from language difference in bilingual children. Understanding the sources of variability in bilingual contexts and the resulting variability in children's skills will help improve language assessment practices by speech-language pathologists. In this article, we review literature on bilingual first language development for children under 5 years of age. We describe the rate of development in single and total language growth, we describe effects of quantity of input and quality of input on growth, and we describe effects of family composition on language input and language growth in bilingual children. We provide recommendations for language assessment of young bilingual children and consider implications for optimizing children's dual language development. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Approaches and uncertainties in nutrient budgets; Implications for nutrient management and environmental policies

NARCIS (Netherlands)

Oenema, O.; Kros, J.; Vries, de W.

2003-01-01

Nutrient budgets of agroecosystems are constructed either (i) to increase the understanding of nutrient cycling, (ii) as performance indicator and awareness raiser in nutrient management and environmental policy, or (iii) as regulating policy instrument to enforce a certain nutrient management

Nutrient environment of red tide- infested waters off south-west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Joseph, T.; Shaiju, P.; Laluraj, C.M.; Balachandran, K.K.; Nair, M.; George, R.; Nair, K.K.C.; Sahayak, S.; Prabhakaran, M.P.

/Accepted: 28 August 2007 /Published online: 19 September 2007 # Springer Science + Business Media B.V. 2007 Abstract The bloom-infested waters along the south- west coast of India were assessed to bring about... tides, a natural phenomenon, are now common in many coastal waters. Various factors contribute to red tide formation such as insolation, wind, rain, salinity and nutrient input from land or by upwelling. Nitrogen and phosphorus are involved in phytoplank...

Tracing salmon-derived nutrients and contaminants in freshwater food webs across a pronounced spawner density gradient.

Science.gov (United States)

Gregory-Eaves, Irene; Demers, J Marc J; Kimpe, Lynda; Krümmel, Eva M; Macdonald, Robie W; Finney, Bruce P; Blais, Jules M

2007-06-01

Many have demonstrated that anadromous Pacific salmon are significant vectors of nutrients from the ocean to freshwaters. Recently. however, it has been recognized that salmon spawners also input significant quantities of contaminants. The objectives of this paper are to delineate the extent to which salmon-derived nutrients are integrated into the freshwater food web using delta(15)N and delta(13)C and to assess the influence of the salmon pathway in the accumulation of contaminants in rainbow trout (Oncorhynchus mykiss). We found that the delta(15)N and delta(13)C of food web components were related positively and significantly to sockeye salmon (Oncorhynchus nerka) spawner density. Contaminant concentrations in rainbow trout also positively and significantly were related to sockeye salmon spawner density. These data suggest that the anadromous salmon nutrient and contaminant pathways are related and significantly impact the contaminant burden of resident fish.

Modeling farm nutrient flows in the North China Plain to reduce nutrient losses

NARCIS (Netherlands)

Zhao, Zhanqing; Bai, Zhaohai; Wei, Sha; Ma, Wenqi; Wang, Mengru; Kroeze, Carolien; Ma, Lin

2017-01-01

Years of poor nutrient management practices in the agriculture industry in the North China Plain have led to large losses of nutrients to the environment, causing severe ecological consequences. Analyzing farm nutrient flows is urgently needed in order to reduce nutrient losses. A farm-level

Assessment of Nutrient Stability in Space Foods

Science.gov (United States)

Zwart, S. R.; Perchonok, M.; Braby, L. A.; Kloeris, V. A.; Smith, S. M.

2009-01-01

Maintaining an intact nutrient supply in the food system flown on spacecraft is a critical issue for mission success and crew health and safety. Early polar expeditions and exploration expeditions by sailing vessels have taught us that a deficiency, or excess, of even a single vitamin in the food supply can be catastrophic. Evidence from ground-based research indicates that some vitamins are destroyed and fatty acids are oxidized (and therefore rendered dangerous or useless) by different types of radiation and by conditions of long-term storage. We hypothesize that radiation and long-term storage in the space-flight environment will affect the stability of vitamins, amino acids, and fatty acids in the space food system. The research objectives of our ongoing stability studies are to determine the stability of water- and fat-soluble vitamins, fatty acids, and amino acids in the space food supply before and after space flight on the International Space Station (ISS). Foods were analyzed after 2 weeks (a flight control), 11, 19, and 28 months of flight. Along with the space-flown foods, ground-based controls matched for time, light, and temperature are analyzed. The flight studies complement planned ground-based studies of the effects of radiation on vitamins, amino acids, and fatty acids. Flight studies are needed because a model based on ground-based data cannot predict all of the effects of the space-flight environment. Flight studies provide a more accurate test system to determine the effects on these nutrients of the temperature, and radiation conditions in the space-flight environment. Ground studies are required to evaluate longer missions and higher radiation levels expected outside low-Earth orbit. In addition to providing information about nutrient stability in space, the results of these studies will help NASA determine if a need exists to develop special packaging that can ensure stability of foods and nutrients in space, or if further studies of nutrient

Microbial enzyme activity, nutrient uptake and nutrient limitation in forested streams

Science.gov (United States)

Brian H. Hill; Frank H. McCormick; Bret C. Harvey; Sherri L. Johnson; Melvin L. Warren; Colleen M. Elonen

2010-01-01

The flow of organic matter and nutrients from catchments into the streams draining them and the biogeochemical transformations of organic matter and nutrients along flow paths are fundamental processes instreams (Hynes,1975; Fisher, Sponseller & Heffernan, 2004). Microbial biofilms are often the primary interface for organic matter and nutrient uptake and...

Nutrient input through submarine groundwater discharge in two major Chinese estuaries: the Pearl River Estuary and the Changjiang River Estuary

Science.gov (United States)

Liu, Jianan; Du, Jinzhou; Wu, Ying; Liu, Sumei

2018-04-01

In this study, we used a 224Ra mass balance model to evaluate the importance of submarine groundwater discharge (SGD) for the budgets of biogenic elements in two major Chinese estuaries: the Pearl River Estuary (PRE) and the Changjiang River Estuary (CRE). The apparent water age in the PRE was estimated to be 4.8 ± 1.1 days in the dry season and 1.8 ± 0.6 days in the wet season using a physical model based on the tidal prism. In the dry season, the water age in the CRE was estimated to be 11.7 ± 3.0 days using the 224Ra/223Ra activities ratios apparent age model. By applying the 224Ra mass balance model, we obtained calculations of the SGD flow in the PRE of (4.5-10) × 108 m3 d-1 (0.23-0.50 m3 m-2 d-1) and (1.2-2.7) × 108 m3 d-1 (0.06-0.14 m3 m-2 d-1) in the dry season and wet season, respectively, and the estimated SGD flux was (4.6-11) × 109 m3 d-1 (0.18-0.45 m3 m-2 d-1) in the dry season of the CRE. In comparison with the nutrient fluxes from the rivers, the SGD-derived nutrient fluxes may play a vital role in controlling the nutrient budgets and stoichiometry in the study areas. The large amount of dissolved inorganic nitrogen and phosphorus fluxes together with high N: P ratios into the PRE and CRE would potentially contribute to eutrophication and the occurrence of red tides along the adjacent waters.

KAJIAN INPUT ENERGI PADA BUDIDAYA PADI METODE SYSTEM OF RICE INTENSIFICATION Studies on Energy Input in System of Rice Intensification Method of Rice Cultivation

Directory of Open Access Journals (Sweden)

Bambang Purwantana

2012-05-01

Full Text Available System of Rice Intensification (SRI is a rice cultivation method that intensively control and manage macro and micro nutrients as well as irrigation. This paper quantifies and compares the energy uses of SRI and conventional rice cultiva- tion systems. The study was conducted at some SRI’s experimental plots in the districts of Sleman, Kulonprogo, and Bantul, the province of Yogyakarta. The calculation of the energy was based on the farmers’ work schedule, the time required for each operation, the number of laborers, machines, tools, fuel, and all materials and inputs used. The result shows that SRI method consumed 35% less energy to conventional rice cultivation. Energy inputs from seed, water, fertilizer and pesticide were significantly reduces. However, there was higher input of human energy due to compost- ing, land preparation and weeding operations. The specific energy of SRI method was 1.96 MJ ha-1 lower than conven- tional method of 4.43 MJ ha-1. In the SRI method, 56.2 % of energy consumed was classified as direct energy and 43.8% was indirect energy. The SRI method used 61.9 % of renewable energy and 38.1 % of non-renewable energy. The working efficiency in composting and weeding operations should be improved in perspective of machine and tools to reduce the use of human energy. ABSTRAK System of Rice Intensification (SRI, merupakan suatu metode budidaya padi secara intensif dengan pengendalian unsur-unsur hara makro dan mikro disertai pengendalian dan pengaturan kebutuhan air. Penelitian ini bertujuan untuk menganalisis penggunaan energi dan mengidentifikasi kemungkinan penghematan energi pada budidaya padi SRI. Pe- nelitian dilakukan di Kabupaten Sleman, Kulonprogo, dan Bantul, Propinsi Daerah Istimewa Yogyakarta. Pengamatan dilakukan pada plot-plot percobaan budidaya padi SRI dengan melakukan audit seluruh input energi selama proses budidaya dan dikomparasikan dengan input energi pada budidaya padi cara konvensional. Hasil

Protection from wintertime rainfall reduces nutrient losses and greenhouse gas emissions during the decomposition of poultry and horse manure-based amendments.

Science.gov (United States)

Maltais-Landry, Gabriel; Neufeld, Katarina; Poon, David; Grant, Nicholas; Nesic, Zoran; Smukler, Sean

2018-04-01

Manure-based soil amendments (herein "amendments") are important fertility sources, but differences among amendment types and management can significantly affect their nutrient value and environmental impacts. A 6-month in situ decomposition experiment was conducted to determine how protection from wintertime rainfall affected nutrient losses and greenhouse gas (GHG) emissions in poultry (broiler chicken and turkey) and horse amendments. Changes in total nutrient concentration were measured every 3 months, changes in ammonium (NH 4 + ) and nitrate (NO 3 - ) concentrations every month, and GHG emissions of carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) every 7-14 days. Poultry amendments maintained higher nutrient concentrations (except for K), higher emissions of CO 2 and N 2 O, and lower CH 4 emissions than horse amendments. Exposing amendments to rainfall increased total N and NH 4 + losses in poultry amendments, P losses in turkey and horse amendments, and K losses and cumulative N 2 O emissions for all amendments. However, it did not affect CO 2 or CH 4 emissions. Overall, rainfall exposure would decrease total N inputs by 37% (horse), 59% (broiler chicken), or 74% (turkey) for a given application rate (wet weight basis) after 6 months of decomposition, with similar losses for NH 4 + (69-96%), P (41-73%), and K (91-97%). This study confirms the benefits of facilities protected from rainfall to reduce nutrient losses and GHG emissions during amendment decomposition. The impact of rainfall protection on nutrient losses and GHG emissions was monitored during the decomposition of broiler chicken, turkey, and horse manure-based soil amendments. Amendments exposed to rainfall had large ammonium and potassium losses, resulting in a 37-74% decrease in N inputs when compared with amendments protected from rainfall. Nitrous oxide emissions were also higher with rainfall exposure, although it had no effect on carbon dioxide and methane emissions

Manipulating stored phonological input during verbal working memory

Science.gov (United States)

Cogan, Gregory B.; Iyer, Asha; Melloni, Lucia; Thesen, Thomas; Friedman, Daniel; Doyle, Werner; Devinsky, Orrin; Pesaran, Bijan

2016-01-01

Verbal working memory (vWM), involves storing and manipulating information in phonological sensory input. An influential theory of vWM proposes that manipulation is carried out by a central executive while storage is performed by two interacting systems: A phonological input buffer that captures sound-based information and an articulatory rehearsal system that controls speech motor output. Whether, when, and how neural activity in the brain encodes these components remains unknown. Here, we read-out the contents of vWM from neural activity in human subjects as they manipulate stored speech sounds. As predicted, we identify storage systems that contain both phonological sensory and articulatory motor representations. Surprisingly however, we find that manipulation does not involve a single central executive but rather involves two systems with distinct contributions to successful manipulation. We propose, therefore, that multiple subsystems comprise the central executive needed to manipulate stored phonological input for articulatory motor output in vWM. PMID:27941789

Observer-Based Perturbation Extremum Seeking Control with Input Constraints for Direct-Contact Membrane Distillation Process

KAUST Repository

Eleiwi, Fadi; Laleg-Kirati, Taous-Meriem

2017-01-01

has pump flow rates as process inputs. The objective of the controller is to optimize the trade-off between the permeate mass flux and the energy consumption by the pumps inside the process. Cases of single and multiple control inputs are considered

Beaver-mediated lateral hydrologic connectivity, fluvial carbon and nutrient flux, and aquatic ecosystem metabolism

Science.gov (United States)

Wegener, Pam; Covino, Tim; Wohl, Ellen

2017-06-01

River networks that drain mountain landscapes alternate between narrow and wide valley segments. Within the wide segments, beaver activity can facilitate the development and maintenance of complex, multithread planform. Because the narrow segments have limited ability to retain water, carbon, and nutrients, the wide, multithread segments are likely important locations of retention. We evaluated hydrologic dynamics, nutrient flux, and aquatic ecosystem metabolism along two adjacent segments of a river network in the Rocky Mountains, Colorado: (1) a wide, multithread segment with beaver activity; and, (2) an adjacent (directly upstream) narrow, single-thread segment without beaver activity. We used a mass balance approach to determine the water, carbon, and nutrient source-sink behavior of each river segment across a range of flows. While the single-thread segment was consistently a source of water, carbon, and nitrogen, the beaver impacted multithread segment exhibited variable source-sink dynamics as a function of flow. Specifically, the multithread segment was a sink for water, carbon, and nutrients during high flows, and subsequently became a source as flows decreased. Shifts in river-floodplain hydrologic connectivity across flows related to higher and more variable aquatic ecosystem metabolism rates along the multithread relative to the single-thread segment. Our data suggest that beaver activity in wide valleys can create a physically complex hydrologic environment that can enhance hydrologic and biogeochemical buffering, and promote high rates of aquatic ecosystem metabolism. Given the widespread removal of beaver, determining the cumulative effects of these changes is a critical next step in restoring function in altered river networks.

Nutrient Status Assessment in Individuals and Populations for Healthy Aging—Statement from an Expert Workshop

Directory of Open Access Journals (Sweden)

Szabolcs Péter

2015-12-01

Full Text Available A workshop organized by the University Medical Center Groningen addressed various current issues regarding nutrient status of individuals and populations, tools and strategies for its assessment, and opportunities to intervene. The importance of nutrient deficiencies and information on nutrient status for health has been illustrated, in particular for elderly and specific patient groups. The nutrient profile of individuals can be connected to phenotypes, like hypertension or obesity, as well as to socio-economic data. This approach provides information on the relationship between nutrition (nutrient intake and status and health outcomes and, for instance, allows us to use the findings to communicate and advocate a healthy lifestyle. Nutrition is complex: a broader profile of nutrients should be considered rather than focusing solely on a single nutrient. Evaluating food patterns instead of intake of individual nutrients provides better insight into relationships between nutrition and health and disease. This approach would allow us to provide feedback to individuals about their status and ways to improve their nutritional habits. In addition, it would provide tools for scientists and health authorities to update and develop public health recommendations.

Estimating nutrient releases from agriculture in China: An extended substance flow analysis framework and a modeling tool

International Nuclear Information System (INIS)

Chen, M.; Chen, J.; Sun, F.

2010-01-01

Agriculture related pollution has attracted the attention of policy makers as well as scientists in China as its contribution to water impairment has increased, and quantitative information at the national and regional levels is being sought to support decision making. However, traditional approaches are either time-consuming, expensive (e.g. national surveys) or oversimplified and crude (e.g. coefficient methods). Therefore, this study proposed an extended substance flow analysis (SFA) framework to estimate nutrient releases from agricultural and rural activities in China by depicting the nutrient flows in Chinese agro-ecosystems. The six-step process proposed herein includes: (a) system definition; (b) model development; (c) database development; (d) model validation; (e) results interpretation; and (f) uncertainty analysis. The developed Eubolism (Elementary Unit based nutrient Balance mOdeLIng in agro-ecoSysteM) model combined a nutrient balance module with an emission inventory module to quantify the nutrient flows in the agro-ecosystem. The model was validated and then applied to estimate the total agricultural nutrient loads, identify the contribution of different agricultural and rural activities and different land use types to the total loads, and analyze the spatial pattern of agricultural nutrient emissions in China. These results could provide an entire picture of agricultural pollution at the national level and be used to support policy making. Furthermore, uncertainties associated with the structure of the elementary units, spatial resolution, and inputs/parameters were also analyzed to evaluate the robustness of the model results.

Design, Fabrication, and Modeling of a Novel Dual-Axis Control Input PZT Gyroscope

Directory of Open Access Journals (Sweden)

Cheng-Yang Chang

2017-10-01

Full Text Available Conventional gyroscopes are equipped with a single-axis control input, limiting their performance. Although researchers have proposed control algorithms with dual-axis control inputs to improve gyroscope performance, most have verified the control algorithms through numerical simulations because they lacked practical devices with dual-axis control inputs. The aim of this study was to design a piezoelectric gyroscope equipped with a dual-axis control input so that researchers may experimentally verify those control algorithms in future. Designing a piezoelectric gyroscope with a dual-axis control input is more difficult than designing a conventional gyroscope because the control input must be effective over a broad frequency range to compensate for imperfections, and the multiple mode shapes in flexural deformations complicate the relation between flexural deformation and the proof mass position. This study solved these problems by using a lead zirconate titanate (PZT material, introducing additional electrodes for shielding, developing an optimal electrode pattern, and performing calibrations of undesired couplings. The results indicated that the fabricated device could be operated at 5.5±1 kHz to perform dual-axis actuations and position measurements. The calibration of the fabricated device was completed by system identifications of a new dynamic model including gyroscopic motions, electromechanical coupling, mechanical coupling, electrostatic coupling, and capacitive output impedance. Finally, without the assistance of control algorithms, the “open loop sensitivity” of the fabricated gyroscope was 1.82 μV/deg/s with a nonlinearity of 9.5% full-scale output. This sensitivity is comparable with those of other PZT gyroscopes with single-axis control inputs.

Design, Fabrication, and Modeling of a Novel Dual-Axis Control Input PZT Gyroscope.

Science.gov (United States)

Chang, Cheng-Yang; Chen, Tsung-Lin

2017-10-31

Conventional gyroscopes are equipped with a single-axis control input, limiting their performance. Although researchers have proposed control algorithms with dual-axis control inputs to improve gyroscope performance, most have verified the control algorithms through numerical simulations because they lacked practical devices with dual-axis control inputs. The aim of this study was to design a piezoelectric gyroscope equipped with a dual-axis control input so that researchers may experimentally verify those control algorithms in future. Designing a piezoelectric gyroscope with a dual-axis control input is more difficult than designing a conventional gyroscope because the control input must be effective over a broad frequency range to compensate for imperfections, and the multiple mode shapes in flexural deformations complicate the relation between flexural deformation and the proof mass position. This study solved these problems by using a lead zirconate titanate (PZT) material, introducing additional electrodes for shielding, developing an optimal electrode pattern, and performing calibrations of undesired couplings. The results indicated that the fabricated device could be operated at 5.5±1 kHz to perform dual-axis actuations and position measurements. The calibration of the fabricated device was completed by system identifications of a new dynamic model including gyroscopic motions, electromechanical coupling, mechanical coupling, electrostatic coupling, and capacitive output impedance. Finally, without the assistance of control algorithms, the "open loop sensitivity" of the fabricated gyroscope was 1.82 μV/deg/s with a nonlinearity of 9.5% full-scale output. This sensitivity is comparable with those of other PZT gyroscopes with single-axis control inputs.

Recovery from disturbance requires resynchronization of ecosystem nutrient cycles.

Science.gov (United States)

Rastetter, E B; Yanai, R D; Thomas, R Q; Vadeboncoeur, M A; Fahey, T J; Fisk, M C; Kwiatkowski, B L; Hamburg, S P

2013-04-01

Nitrogen (N) and phosphorus (P) are tightly cycled in most terrestrial ecosystems, with plant uptake more than 10 times higher than the rate of supply from deposition and weathering. This near-total dependence on recycled nutrients and the stoichiometric constraints on resource use by plants and microbes mean that the two cycles have to be synchronized such that the ratio of N:P in plant uptake, litterfall, and net mineralization are nearly the same. Disturbance can disrupt this synchronization if there is a disproportionate loss of one nutrient relative to the other. We model the resynchronization of N and P cycles following harvest of a northern hardwood forest. In our simulations, nutrient loss in the harvest is small relative to postharvest losses. The low N:P ratio of harvest residue results in a preferential release of P and retention of N. The P release is in excess of plant requirements and P is lost from the active ecosystem cycle through secondary mineral formation and leaching early in succession. Because external P inputs are small, the resynchronization of the N and P cycles later in succession is achieved by a commensurate loss of N. Through succession, the ecosystem undergoes alternating periods of N limitation, then P limitation, and eventually co-limitation as the two cycles resynchronize. However, our simulations indicate that the overall rate and extent of recovery is limited by P unless a mechanism exists either to prevent the P loss early in succession (e.g., P sequestration not stoichiometrically constrained by N) or to increase the P supply to the ecosystem later in succession (e.g., biologically enhanced weathering). Our model provides a heuristic perspective from which to assess the resynchronization among tightly cycled nutrients and the effect of that resynchronization on recovery of ecosystems from disturbance.

Multi-method comparison of carrot quality from a conventional and three organic cropping systems with increasing levels of nutrient recycling

DEFF Research Database (Denmark)

Paoletti, Flavio; Raffo´, Antonio; Kristensen, Hanne Lakkenborg

2012-01-01

BACKGROUND: There is a need to advance the study of the effects of organic and conventional systems on product quality. In particular, little is known about the importance of different farming practices concerning nutrient cycling and the use of external inputs within organic farming for the qual...

Multiple constraint modeling of nutrient cycling stoichiometry following forest clearing and pasture abandonment in the Eastern Amazon

Science.gov (United States)

Davidson, Eric; Nifong, Rachel

2017-04-01

While deforestation has declined since its peak, land-use change continues to modify Amazonian landscapes. The responses and feedbacks of biogeochemical cycles to these changes play an important role in determining possible future trajectories of ecosystem function and for land stewardship through effects on rates of secondary forest regrowth, soil emissions of greenhouse gases, inputs of nutrients to groundwater and streamwater, and nutrient management in agroecosystems. Here we present a new synthetic analyses of data from the NASA-supported LBA-ECO project and others datasets on nutrient cycling in cattle pastures, secondary forests, and mature forests at Paragominas, Pará, Brazil. We have developed a stoichiometric model relating C-N-P interactions during original forest clearing, extensive and intensive pasture management, and secondary forest regrowth, constrained by multiple observations of ecosystem stocks and fluxes in each land use. While P is conservatively cycled in all land uses, we demonstrate that pyrolyzation of N during pasture formation and during additional burns for pasture management depletes available-N pools, consistent with observations of lower rates of N leaching and trace gas emission and consistent with secondary forest growth responses to experimental N amendments. The soils store large stocks of N and P, and our parameterization of available forms of these nutrients for steady-state dynamics in the mature forest yield reasonable estimates of net N and P mineralization available for grasses and secondary forest species at rates consistent with observed biomass accumulation and productivity in these modified ecosystems. Because grasses and forests have much different demands for N relative to P, the land use has important biogeochemical impacts. The model demonstrates the need for periodic P inputs for sustainable pasture management and for a period of significant biological N fixation for early-to-mid-successional secondary forest

In the other 90%: phytoplankton responses to enhanced nutrient availability in the Great Barrier Reef Lagoon

International Nuclear Information System (INIS)

Furnas, Miles; Mitchell, Alan; Skuza, Michele; Brodie, Jon

2005-01-01

Our view of how water quality effects ecosystems of the Great Barrier Reef (GBR) is largely framed by observed or expected responses of large benthic organisms (corals, algae, seagrasses) to enhanced levels of dissolved nutrients, sediments and other pollutants in reef waters. In the case of nutrients, however, benthic organisms and communities are largely responding to materials which have cycled through and been transformed by pelagic communities dominated by micro-algae (phytoplankton), protozoa, flagellates and bacteria. Because GBR waters are characterised by high ambient light intensities and water temperatures, inputs of nutrients from both internal and external sources are rapidly taken up and converted to organic matter in inter-reefal waters. Phytoplankton growth, pelagic grazing and remineralisation rates are very rapid. Dominant phytoplankton species in GBR waters have in situ growth rates which range from ∼1 to several doublings per day. To a first approximation, phytoplankton communities and their constituent nutrient content turn over on a daily basis. Relative abundances of dissolved nutrient species strongly indicate N limitation of new biomass formation. Direct ( 15 N) and indirect ( 14 C) estimates of N demand by phytoplankton indicate dissolved inorganic N pools have turnover times on the order of hours to days. Turnover times for inorganic phosphorus in the water column range from hours to weeks. Because of the rapid assimilation of nutrients by plankton communities, biological responses in benthic communities to changed water quality are more likely driven (at several ecological levels) by organic matter derived from pelagic primary production than by dissolved nutrient stocks alone

Impacts of Cover Crops on Water and Nutrient Dynamics in Agroecosystems

Science.gov (United States)

Williard, K.; Swanberg, S.; Schoonover, J.

2013-05-01

Intensive cropping systems of corn (Zea Mays L.) and soybeans (Glycine max) are commonly leaky systems with respect to nitrogen (N). Reactive N outputs from agroecosystems can contribute to eutrophication and hypoxic zones in downstream water bodies and greenhouse gas (N2O) emissions. Incorporating cover crops into temperate agroecosystem rotations has been promoted as a tool to increase nitrogen use efficiency and thus limit reactive N outputs to the environment. Our objective was determine how cereal rye (Secale cereal L.) and annual ryegrass (Lolium multiflorum) cover crops impact nutrient and soil water dynamics in an intensive corn and soybean cropping rotation in central Illinois. Cover crops were planted in mid to late October and terminated in early April prior to corn or soybean planting. In the spring just prior to cover crop termination, soil moisture levels were lower in the cover crop plots compared to no cover plots. This can be a concern for the subsequent crop in relatively dry years, which the Midwestern United States experienced in 2012. No cover plots had greater nutrient leaching below the rooting zone compared to cover crop areas, as expected. The cover crops were likely scavenging nutrients during the fall and early spring and should provide nutrients to the subsequent crop via decomposition and mineralization of the cover crop residue. Over the long term, cover crop systems should produce greater inputs and cycling of carbon and N, increasing the productivity of crops due to the long-term accumulation of soil organic matter. This study demonstrates that there may be short term trade-offs in reduced soil moisture levels that should be considered alongside the long term nutrient scavenging and recycling benefits of cover crops.

Single lens laser beam shaper

Science.gov (United States)

Liu, Chuyu [Newport News, VA; Zhang, Shukui [Yorktown, VA

2011-10-04

A single lens bullet-shaped laser beam shaper capable of redistributing an arbitrary beam profile into any desired output profile comprising a unitary lens comprising: a convex front input surface defining a focal point and a flat output portion at the focal point; and b) a cylindrical core portion having a flat input surface coincident with the flat output portion of the first input portion at the focal point and a convex rear output surface remote from the convex front input surface.

Coupled nutrient cycling determines tropical forest trajectory under elevated CO2.

Science.gov (United States)

Bouskill, N.; Zhu, Q.; Riley, W. J.

2017-12-01

Tropical forests have a disproportionate capacity to affect Earth's climate relative to their areal extent. Despite covering just 12 % of land surface, tropical forests account for 35 % of global net primary productivity and are among the most significant of terrestrial carbon stores. As atmospheric CO2 concentrations increase over the next century, the capacity of tropical forests to assimilate and sequester anthropogenic CO2 depends on limitation by multiple factors, including the availability of soil nutrients. Phosphorus availability has been considered to be the primary factor limiting metabolic processes within tropical forests. However, recent evidence points towards strong spatial and temporal co-limitation of tropical forests by both nitrogen and phosphorus. Here, we use the Accelerated Climate Modeling for Energy (ACME) Land Model (ALMv1-ECA-CNP) to examine how nutrient cycles interact and affect the trajectory of the tropical forest carbon sink under, (i) external nutrient input, (ii) climate (iii) elevated CO2, and (iv) a combination of 1-3. ALMv1 includes recent theoretical advances in representing belowground competition between roots, microbes and minerals for N and P uptake, explicit interactions between the nitrogen and phosphorus cycles (e.g., phosphatase production and nitrogen fixation), the dynamic internal allocation of plant N and P resources, and the integration of global datasets of plant physiological traits. We report nutrient fertilization (N, P, N+P) predictions for four sites in the tropics (El Verde, Puerto Rico, Barro Colorado Island, Panama, Manaus, Brazil and the Osa Peninsula, Coast Rica) to short-term nutrient fertilization (N, P, N+P), and benchmarking of the model against a meta-analysis of forest fertilization experiments. Subsequent simulations focus on the interaction of the carbon, nitrogen, and phosphorus cycles across the tropics with a focus on the implications of coupled nutrient cycling and the fate of the tropical

Influence of Acacia trees on soil nutrient levels in arid lands

Science.gov (United States)

De Boever, Maarten; Gabriels, Donald; Ouessar, Mohamed; Cornelis, Wim

2014-05-01

The potential of scattered trees as keystone structures in restoring degraded environments is gaining importance. Scattered trees have strong influence on their abiotic environment, mainly causing changes in microclimate, water budget and soil properties. They often function as 'nursing trees', facilitating the recruitment of other plants. Acacia raddiana is such a keystone species which persists on the edge of the Sahara desert. The study was conducted in a forest-steppe ecosystem in central Tunisia where several reforestation campaigns with Acacia took place. To indentify the impact of those trees on soil nutrients, changes in nutrient levels under scattered trees of three age stages were examined for the upper soil layer (0-10 cm) at five microsites with increasing distance from the trunk. In addition, changes in soil nutrient levels with depth underneath and outside the canopy were determined for the 0-30 cm soil layer. Higher concentrations of organic matter (OM) were found along the gradient from underneath to outside the canopy for large trees compared to medium and small trees, especially at microsites close to the trunk. Levels of soluble K, electrical conductivity (EC), available P, OM, total C and N decreased whereas pH and levels of soluble Mg increased with increasing distance from tree. Levels of soluble Ca and Na remained unchanged along the gradient. At the microsite closest to the trunk a significant decrease in levels of soluble K, EC, OM, available P, total C and N, while a significant increase in pH was found with increasing depth. The concentration of other nutrients remained unchanged or declined not differently underneath compared to outside the canopy with increasing depth. Differences in nutrient levels were largely driven by greater inputs of organic matter under trees. Hence, Acacia trees can affect the productivity and reproduction of understory species with the latter in term an important source of organic matter. This positive feedback

Effects of mountain tea plantations on nutrient cycling at upstream watersheds

Science.gov (United States)

Lin, T.-C.; Shaner, P.-J. L.; Wang, L.-J.; Shih, Y.-T.; Wang, C.-P.; Huang, G.-H.; Huang, J.-C.

2015-11-01

The expansion of agriculture to rugged mountains can exacerbate negative impacts of agricultural activities on ecosystem function. In this study, we monitored streamwater and rainfall chemistry of mountain watersheds at the Feitsui Reservoir Watershed in northern Taiwan to examine the effects of agriculture on watershed nutrient cycling. We found that the greater the proportion of tea plantation cover, the higher the concentrations of fertilizer-associated ions (NO3-, K+) in streamwater of the four mountain watersheds examined; on the other hand, the concentrations of the ions that are rich in soils (SO42-, Ca2+, Mg2+) did not increase with the proportion of tea plantation cover, suggesting that agriculture enriched fertilizer-associated nutrients in streamwater. Of the two watersheds for which rainfall chemistry was available, the one with higher proportion of tea plantation cover had higher concentrations of ions in rainfall and retained less nitrogen in proportion to input compared to the more pristine watershed, suggesting that agriculture can influence atmospheric deposition of nutrients and a system's ability to retain nutrients. As expected, we found that a forested watershed downstream of agricultural activities can dilute the concentrations of NO3- in streamwater by more than 70 %, indicating that such a landscape configuration helps mitigate nutrient enrichment in aquatic systems even for watersheds with steep topography. We estimated that tea plantation at our study site contributed approximately 450 kg ha-1 yr-1 of NO3-N via streamwater, an order of magnitude greater than previously reported for agricultural lands around the globe, which can only be matched by areas under intense fertilizer use. Furthermore, we constructed watershed N fluxes to show that excessive leaching of N, and additional loss to the atmosphere via volatilization and denitrification can occur under intense fertilizer use. In summary, this study demonstrated the pervasive impacts of

Enhanced Sensitivity to Rapid Input Fluctuations by Nonlinear Threshold Dynamics in Neocortical Pyramidal Neurons.

Science.gov (United States)

Mensi, Skander; Hagens, Olivier; Gerstner, Wulfram; Pozzorini, Christian

2016-02-01

The way in which single neurons transform input into output spike trains has fundamental consequences for network coding. Theories and modeling studies based on standard Integrate-and-Fire models implicitly assume that, in response to increasingly strong inputs, neurons modify their coding strategy by progressively reducing their selective sensitivity to rapid input fluctuations. Combining mathematical modeling with in vitro experiments, we demonstrate that, in L5 pyramidal neurons, the firing threshold dynamics adaptively adjust the effective timescale of somatic integration in order to preserve sensitivity to rapid signals over a broad range of input statistics. For that, a new Generalized Integrate-and-Fire model featuring nonlinear firing threshold dynamics and conductance-based adaptation is introduced that outperforms state-of-the-art neuron models in predicting the spiking activity of neurons responding to a variety of in vivo-like fluctuating currents. Our model allows for efficient parameter extraction and can be analytically mapped to a Generalized Linear Model in which both the input filter--describing somatic integration--and the spike-history filter--accounting for spike-frequency adaptation--dynamically adapt to the input statistics, as experimentally observed. Overall, our results provide new insights on the computational role of different biophysical processes known to underlie adaptive coding in single neurons and support previous theoretical findings indicating that the nonlinear dynamics of the firing threshold due to Na+-channel inactivation regulate the sensitivity to rapid input fluctuations.

Coupling hydrological and impact assessment models to explore nutrient cycling in freshwater systems

Science.gov (United States)

Bouwman, Lex; van Beek, Rens; Beusen, Arthur; Mogollón, José; Middelburg, Jack

2016-04-01

The IMAGE-Global Nutrient Model (GNM) is a new globally distributed, spatially explicit model in which the hydrology model PCR-GLOBWB is coupled to the integrated assessment model IMAGE to simulate nitrogen (N) and phosphorus (P) delivery, and then with a spiraling ecological approach to simulating instream biogeochemistry. Routing the water with dissolved and suspended N and P from upstream grid cells occurs simultaneous with N and P delivery to water bodies within grid cells from diffuse and point sources (wastewater). IMAGE-GNM describes the following diffuse sources associated with the water flow: surface runoff, shallow and deep groundwater, riparian zones. Depending on the landscape features, all these flows may be present within one grid cell. Furthermore, diffuse N and P inputs occur through allochtonous organic matter inputs via litterfall in (temporarily) inundated river floodplains, and atmospheric deposition. In the spiraling concept, the residence time of the water and nutrient uptake velocity determine N and P retention in water bodies. Validation of model results with observations yields acceptable agreement given the global scale of the uncalibrated model. Sensitivity analysis shows shifts in the importance of the different sources, with decreasing importance of natural sources and increasing influence of wastewater and agriculture. IMAGE-GNM can be employed to study the interaction between society and the environment over prolonged time periods. Here we show results for the full 20th century.

Intrahousehold Allocation of Nutrients in Rural India: Are Boys Favored? Do Parents Exhibit Inequality Aversion?

OpenAIRE

Behrman, Jere R

1988-01-01

This paper develops a multinutrient input, multihealth related outcome model of intrahousehold nutrient allocation that permits identification of gender preferences and equity-productivity tradeoffs. Estimates for rural South India suggest that parents display male preference during the lean season, particularly in lower-caste households. Parents also exhibit inequality aversion so pure investment models may be misleading, though such inequality aversion is less in the lean season than estima...

On-grid and Off-grid Operation of Multi-Input Single-Output DC/DC Converter based Fuel Cell Generation System

Directory of Open Access Journals (Sweden)

Noroozian

2009-06-01

Full Text Available This paper presents the modeling and simulation of a proton exchange membrane fuel cell (PEMFC generation system for off-grid and on-grid operation and configuration. A fuel cell DG system consists of a fuel cell power plant, a DC/DC converter and a DC/AC inverter. The dynamic model for fuel cell array and its power electronic interfacing are presented also a multi-input single output (MISO DC/DC converter and its control scheme is proposed and analyzed. This DC/DC converter is capable of interfacing fuel cell arrays to the DC/AC inverter. Also the mathematical model of the inverter is obtained by using average technique. Then the novel control strategy of DC/AC inverter for different operating conditions is demonstrated. The simulation results show the effectiveness of the suggested control systems under both on-grid and off-grid operation modes.

Numerical simulations of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay, Indonesia.

Science.gov (United States)

van der Wulp, Simon A; Damar, Ario; Ladwig, Norbert; Hesse, Karl-J

2016-09-30

The present application of numerical modelling techniques provides an overview of river discharges, nutrient flux and nutrient dispersal in Jakarta Bay. A hydrological model simulated river discharges with a total of 90 to 377m(3)s(-1) entering Jakarta Bay. Daily total nitrogen and total phosphorus loads ranged from 40 to 174tons and 14 to 60tons, respectively. Flow model results indicate that nutrient gradients are subject to turbulent mixing by tides and advective transport through circulation driven by wind, barotropic and baroclinic pressure gradients. The bulk of nutrient loads originate from the Citarum and Cisadane rivers flowing through predominantly rural areas. Despite lower nutrient loads, river discharges from the urban area of Jakarta exhibit the highest impact of nutrient concentrations in the near shore area of Jakarta Bay and show that nutrient concentrations were not only regulated by nutrient loads but were strongly regulated by initial river concentrations and local flow characteristics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modeling Nutrient Release in the Tai Lake Basin of China: Source Identification and Policy Implications

Science.gov (United States)

Liu, Beibei; Liu, Heng; Zhang, Bing; Bi, Jun

2013-03-01

Because nutrient enrichment has become increasingly severe in the Tai Lake Basin of China, identifying sources and loads is crucial for watershed nutrient management. This paper develops an empirical framework to estimate nutrient release from five major sectors, which requires fewer input parameters and produces acceptable accuracy. Sectors included are industrial manufacturing, livestock breeding (industrial and family scale), crop agriculture, household consumption (urban and rural), and atmospheric deposition. Results show that in the basin (only the five sectors above), total nutrient loads of nitrogen (N) and phosphorus (P) into aquatic systems in 2008 were 33043.2 tons N a-1 and 5254.4 tons P a-1, and annual area-specific nutrient loads were 1.94 tons N km-2 and 0.31 tons P km-2. Household consumption was the major sector having the greatest impact (46 % in N load, 47 % in P load), whereas atmospheric deposition (18 %) and crop agriculture (15 %) sectors represented other significant proportions of N load. The load estimates also indicate that 32 % of total P came from the livestock breeding sector, making it the second largest phosphorus contributor. According to the nutrient pollution sectors, six best management practices are selected for cost-effectiveness analysis, and feasible options are recommended. Overall, biogas digester construction on industrial-scale farms is proven the most cost-effective, whereas the building of rural decentralized facilities is the best alternative under extreme financial constraint. However, the reduction potential, average monetary cost, and other factors such as risk tolerance of policy makers should all be considered in the actual decision-making process.

Automated pH Control of Nutrient Solution in a Hydroponic Plant Growth System

Science.gov (United States)

Smith, B.; Dogan, N.; Aglan, H.; Mortley, D.; Loretan, P.

1998-01-01

Over, the years, NASA has played an important role in providing to and the development of automated nutrient delivery and monitoring, systems for growing crops hydroponically for long term space missions. One example are the systems used in the Biomass Production Chamber (BPC) at Kennedy Space Center (KSC). The current KSC monitoring system is based on an engineering workstation using standard analog/digital input/output hardware and custom written software. The monitoring system uses completely separate sensors to provide a check of control sensor accuracy and has the ability to graphically display and store data form past experiment so that they are available for data analysis [Fortson, 1992]. In many cases, growing systems have not been fitted with the kind of automated control systems as used at KSC. The Center for Food and Environmental Systems for Human Exploration of Space (CFESH) located on the campus of Tuskegee University, has effectively grown sweetpotatoes and peanuts hydroponically for the past five years. However they have adjusted the pH electrical conductivity and volume of the hydroponic nutrient solution only manually at times when the solution was to be replenished or changed out according to its protocol (e.g. one-week, two-week, or two-day cycle). But the pH of the nutrient solution flowing through the channel is neither known nor controlled between the update, change out, or replenishment period. Thus, the pH of the nutrient solution is not held at an optimum level over the span of the plant's growth cycle. To solve this dilemma, an automated system for the control and data logging of pH data relative to sweetpotato production using the nutrient film technique (NFT) has been developed, This paper discusses a microprocessor-based system, which was designed to monitor, control, and record the pH of a nutrient solution used for growing sweetpotatoes using NFT.

Quantifying stream nutrient uptake from ambient to saturation with instantaneous tracer additions

Science.gov (United States)

Covino, T. P.; McGlynn, B. L.; McNamara, R.

2009-12-01

Stream nutrient tracer additions and spiraling metrics are frequently used to quantify stream ecosystem behavior. However, standard approaches limit our understanding of aquatic biogeochemistry. Specifically, the relationship between in-stream nutrient concentration and stream nutrient spiraling has not been characterized. The standard constant rate (steady-state) approach to stream spiraling parameter estimation, either through elevating nutrient concentration or adding isotopically labeled tracers (e.g. 15N), provides little information regarding the stream kinetic curve that represents the uptake-concentration relationship analogous to the Michaelis-Menten curve. These standard approaches provide single or a few data points and often focus on estimating ambient uptake under the conditions at the time of the experiment. Here we outline and demonstrate a new method using instantaneous nutrient additions and dynamic analyses of breakthrough curve (BTC) data to characterize the full relationship between spiraling metrics and nutrient concentration. We compare the results from these dynamic analyses to BTC-integrated, and standard steady-state approaches. Our results indicate good agreement between these three approaches but we highlight the advantages of our dynamic method. Specifically, our new dynamic method provides a cost-effective and efficient approach to: 1) characterize full concentration-spiraling metric curves; 2) estimate ambient spiraling metrics; 3) estimate Michaelis-Menten parameters maximum uptake (Umax) and the half-saturation constant (Km) from developed uptake-concentration kinetic curves, and; 4) measure dynamic nutrient spiraling in larger rivers where steady-state approaches are impractical.

Monitoring plant tissue nitrogen isotopes to assess nearshore inputs of nitrogen to Lake Crescent, Olympic National Park, Washington

Science.gov (United States)

Cox, Stephen E.; Moran, Patrick W.; Huffman, Raegan L.; Fradkin, Steven C.

2016-05-31

Mats of filamentous-periphytic algae present in some nearshore areas of Lake Crescent, Olympic National Park, Washington, may indicate early stages of eutrophication from nutrient enrichment of an otherwise highly oligotrophic lake. Natural abundance ratios of stable isotopes of nitrogen (δ15N) measured in plant tissue growing in nearshore areas of the lake indicate that the major source of nitrogen used by these primary producing plants is derived mainly from atmospherically fixed nitrogen in an undeveloped forested ecosystem. Exceptions to this pattern occurred in the Barnes Point area where elevated δ15N ratios indicate that effluent from septic systems also contribute nitrogen to filamentous-periphytic algae growing in the littoral zone of that area. Near the Lyre River outlet of Lake Crescent, the δ15N of filamentous-periphytic algae growing in close proximity to the spawning areas of a unique species of trout show little evidence of elevated δ15N indicating that nitrogen from on-site septic systems is not a substantial source of nitrogen for these plants. The δ15N data corroborate estimates that nitrogen input to Lake Crescent from septic sources is comparatively small relative to input from motor vehicle exhaust and vegetative sources in undeveloped forests, including litterfall, pollen, and symbiotic nitrogen fixation. The seasonal timing of blooms of filamentous-periphytic algal near the lake shoreline is also consistent with nitrogen exported from stands of red alder trees (Alnus rubra). Isotope biomonitoring of filamentous-periphytic algae may be an effective approach to monitoring the littoral zone for nutrient input to Lake Crescent from septic sources.

Remote Sensing Analysis of Malawi's Agricultural Inputs Subsidy and Climate Variability Impacts on Productivity

Science.gov (United States)

Galford, G. L.; Fiske, G. J.; Sedano, F.; Michelson, H.

2016-12-01

Agriculture in sub-Saharan Africa is characterized by smallholder production and low yields ( 1 ton ha-1 year-1 since records began in 1961) for staple food crops such as maize (Zea mays). Many years of low-input farming have depleted much of the region's agricultural land of critical soil carbon and nitrogen, further reducing yield potentials. Malawi is a 98,000 km2 subtropical nation with a short rainy season from November to May, with most rainfall occurring between December and mid-April. This short growing season supports the cultivation of one primary crop, maize. In Malawi, many smallholder farmers face annual nutrient deficits as nutrients removed as grain harvest and residues are beyond replenishment levels. As a result, Malawi has had stagnant maize yields averaging 1.2 ton ha-1 year-1 for decades. After multiple years of drought and widespread hunger in the early 2000s, Malawi introduced an agricultural input support program (fertilizer and seed subsidy) in time for the 2006 harvest that was designed to restore soil nutrients, improve maize production, and decrease dependence on food aid. Malawi's subsidy program targets 50-67% of smallholder farmers who cultivate half a hectare or less, yet collectively supply 80% of the country's maize. The country has achieved significant increases in crop yields (now 2 tons/ha/year) and, as our analysis shows, benefited from a new resilience against drought. We utilized Landsat time series to determine cropland extent from 2000-present and identify areas of marginal and/or intermittent production. We found a strong latitudinal gradient of precipitation variability from north to south in CHIRPS data. We used the precipitation variability to normalize trends in a productivity proxy derived from MODIS EVI. After normalization of productivity to precipitation variability, we found significant productivity trends correlated to subsidy distribution. This work was conducted with Google's Earth Engine, a cloud-based platform

Atmospheric deposition of nutrients to north Florida rivers: A multivariate statistical analysis. Final report. Master's thesis

International Nuclear Information System (INIS)

Fu, J.

1991-01-01

Atmospheric nutrient input to the Apalachicola Bay estuary was studied because it has been demonstrated that atmospheric deposition can be a major source of nutrients to eastern U.S. estuaries. Besides the Apalachicola River, the Sopchoppy and the Ochlockonee were also selected for a comparative analysis. Receptor model, absolute principal of component analysis (APCA), and mass balance methods were applied in the study. The results of the study show that nitrogen is probably not a limiting nutrient in the three rivers because their N:P mole ratios are nearly 3 times higher than the Redfield ratio for photosynthesis. The total atmospheric nitrogen depositions in the three river watershed are at least as great as their river fluxes. In the Apalachicola River, the atmospheric source of nitrogen is found to be several times higher than the largest possible input of urban sewage. Atmospheric deposition, therefore, might be the dominant nitrogen source entering the estuary. The results of APCA show that Apalachicola River water is mainly a mixture of components that correspond in their compositions to aged rain, ground water, and fresh rain. Atmospheric nitrate deposition is the result of the air pollution, i.e., acid rain. The studies also show that the annual average deposition of nitrate has a narrow range, mainly from 5.8 to 11.5 kg/ha/yr in most of the NADP sites in the 8 southeastern states. Since all the software and data sets employed in the study are accessible nationwide, the methods could be applied in other watersheds

Nutrients and clam contamination by Escherichia coli in a meso-tidal coastal lagoon: Seasonal variation in counter cycle to external sources

International Nuclear Information System (INIS)

Botelho, Maria João; Soares, Florbela; Matias, Domitília; Vale, Carlos

2015-01-01

Highlights: • Sources of nutrients and E. coli in Ria Formosa linked to tourism in summer. • Lower nutrient values and clam contamination by E. coli in summer. • Bactericide effect of temperature and solar radiation causes lower E. coli. • Higher biological consumption of nutrients in warmer periods. • Results mirror possible effects of climate changes on coastal lagoons. - Abstract: The clam Ruditapes decussatus was transplanted from a natural recruitment area of Ria Formosa to three sites, surveyed for nutrients in water and sediments. Specimens were sampled monthly for determination of Escherichia coli, condition index and gonadal index. Higher nutrient values in low tide reflect drainage, anthropogenic sources or sediment regeneration, emphasising the importance of water mixing in the entire lagoon driven by the tide. Despite the increase of effluent discharges in summer due to tourism, nutrient concentrations and E. coli in clams were lower in warmer periods. The bactericide effect of temperature and solar radiation was better defined in clams from the inlet channel site than from sites closer to urban effluents. High temperature in summer and torrential freshwater inputs to Ria Formosa may anticipate climate change scenarios for south Europe. Seasonal variation of nutrients and clam contamination may thus point to possible alterations in coastal lagoons and their ecosystem services

Nutrient and dissolved organic carbon removal from water using mining and metallurgical by-products.

Science.gov (United States)

Wendling, Laura A; Douglas, Grant B; Coleman, Shandel; Yuan, Zheng

2012-05-15

Excess nutrient input to water bodies frequently results in algal blooms and development of oxygen deficient conditions. Mining or metallurgical by-products can potentially be utilised as filtration media within water treatment systems such as constructed wetlands, permeable reactive barriers, or drain liners. These materials may offer a cost-effective solution for the removal of nutrients and dissolved organic carbon (DOC) from natural waters. This study investigated steel-making, alumina refining (red mud and red sand) and heavy mineral processing by-products, as well as the low-cost mineral-based material calcined magnesia, in laboratory column trials. Influent water and column effluents were analysed for pH and flow rate, alkalinity, nutrient species and DOC, and a range of major cations and anions. In general, by-products with high Ca or Mg, and to a lesser extent those with high Fe content, were well-suited to nutrient and DOC removal from water. Of the individual materials examined, the heavy mineral processing residue neutralised used acid (NUA) exhibited the highest sorption capacity for P, and removed the greatest proportions of all N species and DOC from influent water. In general, NUA and mixtures containing NUA, particularly those with calcined magnesia or red mud/red sand were the most effective in removing nutrients and DOC from influent water. Post-treatment effluents from columns containing NUA and NUA/steel-making by-product, NUA/red sand and NUA/calcined magnesia mixtures exhibited large reductions in DOC, P and N concentrations and exhibited a shift in nutrient ratios away from potential N- and Si-limitation and towards potential P-limitation. If employed as part of a large-scale water treatment scheme, use of these mining and metallurgical by-products for nutrient removal could result in reduced algal biomass and improved water quality. Identification and effective implementation of mining by-products or blends thereof in constructed wetlands

Influence of genotype and feeding strategy on pig performance, plasma concentrations of micro nutrients, immune responses and faecal microbiota composition of growing-finishing pigs in a forage-based system

DEFF Research Database (Denmark)

Kongsted, Anne Grete; Nørgaard, Jan Værum; Jensen, Søren Krogh

2015-01-01

In free-range pig production it is important to reduce the input of nutrients from supplementary feed to reduce nutrient leaching and improve the resource efficiency of the system. A promising development might be to encourage foraging behaviour of the pigs. However, very little is known about pi...... significantly to the nutritional supply of pigs fed restrictedly with supplementary feed. There are indications that the mineral content of the premix is not needed in a forage-based free-range system but cautious need to be taken with regards to the vitamin A, D, E supply.......In free-range pig production it is important to reduce the input of nutrients from supplementary feed to reduce nutrient leaching and improve the resource efficiency of the system. A promising development might be to encourage foraging behaviour of the pigs. However, very little is known about pigs......) of either a traditional (Tamworth×(Landrace×Yorkshire)) or a ‘modern’ crossbreed (Duroc×(Landrace×Yorkshire)) fed a pelleted diet as supplementary feed either according to recommendations (NORM), or restrictedly with (RES+) or without (RES–) a supplementary vitamin and mineral mixture. The pigs ‘strip...

Quantum design rules for single molecule logic gates.

Science.gov (United States)

Renaud, N; Hliwa, M; Joachim, C

2011-08-28

Recent publications have demonstrated how to implement a NOR logic gate with a single molecule using its interaction with two surface atoms as logical inputs [W. Soe et al., ACS Nano, 2011, 5, 1436]. We demonstrate here how this NOR logic gate belongs to the general family of quantum logic gates where the Boolean truth table results from a full control of the quantum trajectory of the electron transfer process through the molecule by very local and classical inputs practiced on the molecule. A new molecule OR gate is proposed for the logical inputs to be also single metal atoms, one per logical input.

Influence of fresh water, nutrients and DOC in two submarine-groundwater-fed estuaries on the west of Ireland.

Science.gov (United States)

Smith, Aisling M; Cave, Rachel R

2012-11-01

Coastal fresh water sources, which discharge to the sea are expected to be directly influenced by climate change (e.g. increased frequency of extreme weather events). Sea-level rise and changes in rainfall patterns, changes in demand for drinking water and contamination caused by population and land use change, will also have an impact. Coastal waters with submarine groundwater discharge are of particular interest as this fresh water source is very poorly quantified. Two adjacent bays which host shellfish aquaculture sites along the coast of Co. Galway in the west of Ireland have been studied to establish the influence of fresh water inputs on nutrients and dissolved organic carbon (DOC) in each bay. Neither bay has riverine input and both are underlain by the karst limestone of the Burren and are susceptible to submarine groundwater discharge. Water and suspended matter samples were collected half hourly over 13 h tidal cycles over several seasons. Water samples were analysed for nutrients and DOC, while suspended matter was analysed for organic/inorganic content. Temperature and salinity measurements were recorded during each tidal station by SBE 37 MicroCAT conductivity/temperature sensors. Long-term mooring data were used to track freshwater input for Kinvara and Aughinish Bays and compare it with rainfall data. Results show that Kinvara Bay is much more heavily influenced by fresh water input than Aughinish Bay, and this is a strong source of fixed nitrogen to Kinvara Bay. Only during flood events is there a significant input of inorganic nitrogen from fresh water to Aughinish Bay, such as in late November 2009. Fresh water input does not appear to be a significant source of dissolved inorganic phosphate (DIP) to either bay, but is a source of DOC to both bays. C:N ratios of DOC/DON show a clear distinction between marine and terrestrially derived dissolved organic material. Copyright © 2012. Published by Elsevier B.V.

Maximizing recovery of energy and nutrients from urban wastewaters

International Nuclear Information System (INIS)

Selvaratnam, T.; Henkanatte-Gedera, S.M.; Muppaneni, T.; Nirmalakhandan, N.; Deng, S.; Lammers, P.J.

2016-01-01

Historically, UWWs (urban wastewaters) that contain high levels of organic carbon, N (nitrogen), and P (phosphorous) have been considered an environmental burden and have been treated at the expense of significant energy input. With the advent of new pollution abatement technologies, UWWs are now being regarded as a renewable resource from which, useful chemicals and energy could be harvested. This study proposes an integrated, algal-based system that has the potential to treat UWWs to the desired discharge standards in a sustainable manner while recovering high fraction of its energy content as well as its N- and P-contents for use as fertilizers. Key embodiments of the system being proposed are: i) cultivation of an extremophile microalga, Galdieria sulphuraria, in UWW for removal of carbon, N, and P via single-step by mixotrophic metabolism; ii) extraction of energy-rich biocrude and biochar from the cultivated biomass via hydrothermal processing; and, iii) enhancement of biomass productivity via partial recycling of the nutrient-rich AP (aqueous product) from hydrothermal-processed biomass to the cultivation step to optimize productivity, and formulation of fertilizers from the remaining AP. This paper presents a process model to simulate this integrated system, identify the optimal process conditions, and establish ranges for operational parameters. - Highlights: • Developed model for algal system for wastewater treatment/energy production. • Evaluated energy efficiency in algal wastewater treatment/energy production. • Optimized algal wastewater treatment/energy production. • Demonstrated feasibility of energy-positive wastewater treatment.

San Francisco Bay nutrients and plankton dynamics as simulated by a coupled hydrodynamic-ecosystem model

Science.gov (United States)

Liu, Qianqian; Chai, Fei; Dugdale, Richard; Chao, Yi; Xue, Huijie; Rao, Shivanesh; Wilkerson, Frances; Farrara, John; Zhang, Hongchun; Wang, Zhengui; Zhang, Yinglong

2018-06-01

An open source coupled physical-biogeochemical model is developed for San Francisco Bay (SFB) to study nutrient cycling and plankton dynamics as well as to assist ecosystem based management and risk assessment. The biogeochemical model in this study is based on the Carbon, Silicate and Nitrogen Ecosystem (CoSiNE) model, and coupled to the unstructured grid, Semi-Implicit Cross-scale Hydroscience Integrated System Model (SCHISM). The SCHISM-CoSiNE model reproduces the spatial and temporal variability in nutrients and plankton biomass, and its physical and biogeochemical performance is successfully tested using comparisons with shipboard and fixed station observations. The biogeochemical characteristics of the SFB during wet and dry years are investigated by changing the input of the major rivers. River discharges from the Sacramento and San Joaquin Rivers affect the phytoplankton biomass in North SFB through both advection and dilution of nutrient (including ammonium, NH4) concentrations in the river. The reduction in residence time caused by increased inflows can result in decreased biomass accumulation, while the corresponding reduction in NH4 concentration favors the growth of biomass. In addition, the model is used to make a series of sensitivity experiments to examine the response of SFB to changes in 1) nutrient loading from rivers and wastewater treatment plants (WWTPs), 2) a parameter (ψ) defining NH4 inhibition of nitrate (NO3) uptake by phytoplankton, 3) bottom grazing and 4) suspended sediment concentration. The model results show that changes in NH4 input from rivers or WWTPs affect the likelihood of phytoplankton blooms via NH4 inhibition and that the choice of ψ is critical. Bottom grazing simulated here as increased plankton mortality demonstrates the potential for bivalve reduction of chlorophyll biomass and the need to include bivalve grazing in future models. Furthermore, the model demonstrates the need to include sediments and their contribution

Novel Agricultural Conservation System with Sustained Yield and Decreased Water, Nutrient, Energy, and Carbon Footprints

Science.gov (United States)

Hansen, K.; Shukla, S.; Holt, N.; Hendricks, G.; Sishodia, R. P.

2017-12-01

Fresh fruits and vegetables are conventionally grown in raised bed plasticulture (RBP), a high intensity, high input, and high output production system. In 2016, the fresh market plasticulture industry covered 680,000 ha in the US, producing crops (e.g. tomato, peppers, melons, and strawberries) valued at ten billion dollars. To meet the increasing future demand for fresh fruits and vegetables and sustain the production potential of croplands, a transformation of the conventional food-water-energy nexus is essential. A novel agricultural conservation system, compact bed geometry, has been proposed to shift the paradigm in RBP, sustaining yield and decreasing inputs (e.g. water, nutrients, energy, and carbon). Compact bed geometries fit the shape of the wetting front created when water is applied through drip irrigation on the production soil, creating a taller (23-30 cm) and thinner bed (66-41 cm). Two seasons of tomato (single row) and pepper (double row) production, in the environmentally fragile watershed of the Florida Everglades, highlight the potential impact of compact bed geometry on environmental sustainability in agricultural production. No difference in plant growth or yield was detected, with a reduction of 5-50% in irrigation water, up to 20% less N application, 12% less P, 20% less K, and 5-15% less carbon dioxide emissions. The hydrologic benefits of compact bed geometry include 26% less runoff generation, decreased need for active drainage pumping, and increased residence time for irrigation water within the bed, overall decreasing instances of nutrient leaching. A water related co-benefit observed was a reduction in the occurrences of Phytophthora capsici in pepper, which has the potential to reduce yield by as much as 70%. Non-water co-benefits include up to a 250/ ha reduction in production cost, with the potential to save the industry 200 million dollars annually. This economic benefit has led to rapid industry adoption, with more than 20

Micro-halocline enabled nutrient recycling may explain extreme Azolla event in the Eocene Arctic Ocean.

Science.gov (United States)

van Kempen, Monique M L; Smolders, Alfons J P; Lamers, Leon P M; Roelofs, Jan G M

2012-01-01

In order to understand the physicochemical mechanisms that could explain the massive growth of Azolla arctica in the Eocene Arctic Ocean, we carried out a laboratory experiment in which we studied the interacting effects of rain and wind on the development of salinity stratification, both in the presence and in the absence of a dense Azolla cover. Additionally, we carried out a mesocosm experiment to get a better understanding of the nutrient cycling within and beneath a dense Azolla cover in both freshwater and brackish water environments. Here we show that Azolla is able to create a windproof, small-scale salinity gradient in brackish waters, which allows for efficient recycling of nutrients. We suggest that this mechanism ensures the maintenance of a large standing biomass in which additional input of nutrients ultimately result in a further expansion of an Azolla cover. As such, it may not only explain the extent of the Azolla event during the Eocene, but also the absence of intact vegetative Azolla remains and the relatively low burial efficiency of organic carbon during this interval.

Micro-halocline enabled nutrient recycling may explain extreme Azolla event in the Eocene Arctic Ocean.

Directory of Open Access Journals (Sweden)

Monique M L van Kempen

Full Text Available In order to understand the physicochemical mechanisms that could explain the massive growth of Azolla arctica in the Eocene Arctic Ocean, we carried out a laboratory experiment in which we studied the interacting effects of rain and wind on the development of salinity stratification, both in the presence and in the absence of a dense Azolla cover. Additionally, we carried out a mesocosm experiment to get a better understanding of the nutrient cycling within and beneath a dense Azolla cover in both freshwater and brackish water environments. Here we show that Azolla is able to create a windproof, small-scale salinity gradient in brackish waters, which allows for efficient recycling of nutrients. We suggest that this mechanism ensures the maintenance of a large standing biomass in which additional input of nutrients ultimately result in a further expansion of an Azolla cover. As such, it may not only explain the extent of the Azolla event during the Eocene, but also the absence of intact vegetative Azolla remains and the relatively low burial efficiency of organic carbon during this interval.

An input-output energy analysis in greenhouse vegetable production: a case study for Antalya region of Turkey

Energy Technology Data Exchange (ETDEWEB)

Ozkan, Burhan; Akcaoz, Handan [Akdeniz Univ., Dept. of Agricultural Economics, Antalya (Turkey); Kurklu, Ahmet [Akdeniz Univ., Dept. of Agricultural Machinery, Antalya (Turkey)

2004-01-01

The aim of this research was to examine the energy equivalents of inputs and output in greenhouse vegetable production in the Antalya province of Turkey. For this purpose, the data for the production of four greenhouse crops (tomato, cucumber, eggplant and pepper) were collected in eighty-eight greenhouse farms by questionnaire. The results revealed that cucumber production was the most energy intensive of among the four crops investigated. Cucumber production consumed a total of 134.77 GJha{sup -1} followed by tomato with 127.32 GJha{sup -1}. The consumption of energy by eggplants and pepper were 98.68 and 80.25 GJha{sup -1}, respectively. The output-input energy ratio for greenhouse tomato, pepper, cucumber and eggplant were estimated to be 1.26, 0.99, 0.76 and 0.61, respectively. This indicated an intensive use of inputs in greenhouse vegetable production not accompanied by increase in the final product. This can lead to problems associated with these inputs such as global warming, nutrient loading and pesticide pollution. Therefore, there is a need to pursue a new policy to force producers to undertake energy efficient practices to increase the yield without diminishing natural resources. (Author)

Fogwater Inputs to a Cloud Forest in Puerto Rico

Science.gov (United States)

Eugster, W.; Burkard, R.; Holwerda, F.; Bruijnzeel, S.; Scatena, F. N.; Siegwolf, R.

2002-12-01

Fog is highly persistent at upper elevations of humid tropical mountains and is an important pathway for water and nutrient inputs to mountain forest ecosystems. Measurements of fogwater fluxes were performed in the Luquillo mountains of Puerto Rico using the eddy covariance approach and a Caltech-type active strand cloudwater collector. Rainfall and throughfall were collected between 25 June--7 August 2002. Samples of fog, rain, stemflow and throughfall were analyzed for inorganic ion and stable isotope concentrations (δ18O and δD). Initial results indicate that fog inputs can occur during periods without rain and last for up to several days. The isotope ratios in rainwater and fogwater are rather similar, indicative of the proximity of the Carribbean Sea and the close interrelation between the origins of fog and rain at our experimental site. Largest differences in isotope ratios for fog were found between daytime convective and nighttime stable conditions. Throughfall was always exceeding rainfall, indicating (a) the relevance of fogwater inputs and (b) the potentially significant undersampling of rainfall due to relatively high wind speeds (5.7 m/s mean) and the exposition of our field site close to a mountain ridge. Our size-resolved measurements of cloud droplets (40 size bins between 2 and 50 μm aerodynamic diameter) indicate that the liquid water content of fog in the Luquillo mountains is 5 times higher than previously assumed, and thus does not differ from the values reported from other mountain ranges in other climate zones. Average deposition rates are 0.88 mm and 6.5 mm per day for fog and rain, respectively.

Optogenetic stimulation of lateral amygdala input to posterior piriform cortex modulates single-unit and ensemble odor processing

Directory of Open Access Journals (Sweden)

Benjamin eSadrian

2015-12-01

Full Text Available Olfactory information is synthesized within the olfactory cortex to provide not only an odor percept, but also a contextual significance that supports appropriate behavioral response to specific odor cues. The piriform cortex serves as a communication hub within this circuit by sharing reciprocal connectivity with higher processing regions, such as the lateral entorhinal cortex and amygdala. The functional significance of these descending inputs on piriform cortical processing of odorants is currently not well understood. We have employed optogenetic methods to selectively stimulate lateral and basolateral amygdala (BLA afferent fibers innervating the posterior piriform cortex (pPCX to quantify BLA modulation of pPCX odor-evoked activity. Single unit odor-evoked activity of anaesthetized BLA-infected animals was significantly modulated compared with control animal recordings, with individual cells displaying either enhancement or suppression of odor-driven spiking. In addition, BLA activation induced a decorrelation of odor-evoked pPCX ensemble activity relative to odor alone. Together these results indicate a modulatory role in pPCX odor processing for the BLA complex, which could contribute to learned changes in PCX activity following associative conditioning.

Dual-Input Isolated Full-Bridge Boost DC-DC Converter Based on the Distributed Transformers

DEFF Research Database (Denmark)

Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

2012-01-01

In this paper, a new two-input isolated boost dc-dc converter based on a distributed multi-transformer structure which is suitable for hybrid renewable energy systems is investigated and designed. With a novel transformer winding-connecting strategy, the two input ports can be decoupled completely...... and the single-input mode, respectively. The main advantage of the proposed topology is that the four transformers and the secondary rectifiers are fully utilized whether the converter is connected with two input power sources or only one input. Although the four transformers are employed, the nominal powers...... of each transformer and rectifier are both reduced by four times. Furthermore, some special issues on converter design, such as increasing number of the input ports, the magnetic integration and the ground loop decoupling are discussed. A 2 kW prototype was built and tested. Experiments on the converter...

A Novel Coupled State/Input/Parameter Identification Method for Linear Structural Systems

Directory of Open Access Journals (Sweden)

Zhimin Wan

2018-01-01

Full Text Available In many engineering applications, unknown states, inputs, and parameters exist in the structures. However, most methods require one or two of these variables to be known in order to identify the other(s. Recently, the authors have proposed a method called EGDF for coupled state/input/parameter identification for nonlinear system in state space. However, the EGDF method based solely on acceleration measurements is found to be unstable, which can cause the drift of the identified inputs and displacements. Although some regularization methods can be adopted for solving the problem, they are not suitable for joint input-state identification in real time. In this paper, a strategy of data fusion of displacement and acceleration measurements is used to avoid the low-frequency drift in the identified inputs and structural displacements for linear structural systems. Two numerical examples about a plane truss and a single-stage isolation system are conducted to verify the effectiveness of the proposed modified EGDF algorithm.

The global nutrient challenge. From science to public engagement

Energy Technology Data Exchange (ETDEWEB)

Sutton, M.A.; Howard, C.M. [NERC Centre for Ecology and Hydrology, Edinburgh (United Kingdom); Bleeker, A. [Energy research Centre of the Netherlands, Petten (Netherlands); Datta, A. [United Nations Environment Programme, Nairobi (Kenya)

2013-04-15

Among the many environment and development challenges facing humanity, it is fair to say that nutrients do not currently feature so regularly in the newspapers, radio and television. The media tends to prefer easy single issues which affect our daily lives in a clear-cut way. The role of carbon in climate change is a good example. We all depend on climate. Burning fossil fuels makes more carbon dioxide, tending to change temperature and rainfall patterns, to which we can easily relate. The science is complex, but it is a simple message for the public to understand. It does not take long to think of several other easily grasped threats, like urban air pollution, poor drinking water, or even the occurrence of horsemeat in food chains. It is perhaps for these reasons that the role of nutrients in environmental change has received much less public attention. After all, nutrients - including nitrogen, phosphorus and many micronutrients - play multiple roles in our world; they affect many biogeochemical processes and they lead to a plethora of interacting threats. If we are not careful, we can quickly get buried in the complexity of the different ways in which our lives are affected by these elements. The outcome is that it can become hard to convey the science of global nutrient cycles in a way that the public can understand. These are points about which we have given substantial thought as we contributed to a recently launched report Our Nutrient World: The challenge to produce more food and energy with less pollution (Sutton et al., 2013). The report was commissioned by the United Nations Environment Programme (UNEP) and conducted by the Global Partnership on Nutrient Management in cooperation with the International Nitrogen Initiative. The commission was not to provide a full scientific assessment, but rather to develop a global overview of the challenges associated with nutrient management. Drawing on existing knowledge, the aim was to distill the nature of the

Nutrient synchrony in preruminant calves

NARCIS (Netherlands)

Borne, van den J.J.G.C.

2006-01-01

In animal nutrition, the nutrient composition of the daily feed supply is composed to match the nutrient requirements for the desired performance. The time of nutrient availability within a day is usually considered not to affect the fate of nutrients. The aim of this thesis was to evaluate effects

Design, development and validation of software for modelling dietary exposure to food chemicals and nutrients.

Science.gov (United States)

McNamara, C; Naddy, B; Rohan, D; Sexton, J

2003-10-01

The Monte Carlo computational system for stochastic modelling of dietary exposure to food chemicals and nutrients is presented. This system was developed through a European Commission-funded research project. It is accessible as a Web-based application service. The system allows and supports very significant complexity in the data sets used as the model input, but provides a simple, general purpose, linear kernel for model evaluation. Specific features of the system include the ability to enter (arbitrarily) complex mathematical or probabilistic expressions at each and every input data field, automatic bootstrapping on subjects and on subject food intake diaries, and custom kernels to apply brand information such as market share and loyalty to the calculation of food and chemical intake.

Sequential estimation of intrinsic activity and synaptic input in single neurons by particle filtering with optimal importance density

Science.gov (United States)

Closas, Pau; Guillamon, Antoni

2017-12-01

This paper deals with the problem of inferring the signals and parameters that cause neural activity to occur. The ultimate challenge being to unveil brain's connectivity, here we focus on a microscopic vision of the problem, where single neurons (potentially connected to a network of peers) are at the core of our study. The sole observation available are noisy, sampled voltage traces obtained from intracellular recordings. We design algorithms and inference methods using the tools provided by stochastic filtering that allow a probabilistic interpretation and treatment of the problem. Using particle filtering, we are able to reconstruct traces of voltages and estimate the time course of auxiliary variables. By extending the algorithm, through PMCMC methodology, we are able to estimate hidden physiological parameters as well, like intrinsic conductances or reversal potentials. Last, but not least, the method is applied to estimate synaptic conductances arriving at a target cell, thus reconstructing the synaptic excitatory/inhibitory input traces. Notably, the performance of these estimations achieve the theoretical lower bounds even in spiking regimes.

Canopy and leaf composition drive patterns of nutrient release from pruning residues in a coffee agroforest.

Science.gov (United States)

Tully, Katherine L; Lawrence, Deborah

2012-06-01

In a coffee agroforest, the crop is cultivated under the shade of fruit-bearing and nitrogen (N)-fixing trees. These trees are periodically pruned to promote flowering and fruiting as well as to make nutrients stored in tree biomass available to plants. We investigated the effect of canopy composition and substrate quality on decomposition rates and patterns of nutrient release from pruning residues in a coffee agroforest located in Costa Rica's Central Valley. Initial phosphorus (P) release was enhanced under a canopy composed solely of N-fixing, Erythrina poeppigiana compared to a mixed canopy of Erythrina and Musa acuminata (banana). Both initial and final N release were similar under the two canopy types. However, after five months of decomposition, a higher proportion of initial N had been released under the single canopy. Although patterns of decomposition and nutrient release were not predicted by initial substrate quality, mass loss in leaf mixtures rates were well predicted by mean mass loss of their component species. This study identifies specific pruning regimes that may regulate N and P release during crucial growth periods, and it suggests that strategic pruning can enhance nutrient availability. For example, during the onset of rapid fruit growth, a two-species mixture may release more P than a three-species mixture. However, by the time of the harvest, the two- and three-species mixtures have released roughly the same amount of N and P. These nutrients do not always follow the same pattern, as N release can be maximized in single-species substrates, while P release is often facilitated in species mixtures. Our study indicates the importance of management practices in mediating patterns of nutrient release. Future research should investigate how canopy composition and farm management can also mediate on-farm nutrient losses.

Performance Evaluation of Type-3 PLLs Under Wide Variation in Input Voltage and Frequency

DEFF Research Database (Denmark)

Aravind, C. K.; Rani, B.Indu; Chakkarapani, M.

2017-01-01

This paper presents a detailed analysis of Type-3 PLL under wide variation in input voltage and frequency. Using small signal modeling, the performance of both single loop and dual loop type-3 PLL for variation in input voltage and frequency is studied. The analysis shows that for the same bandwi...... verified by implementing in ALTERA cyclone II FPGA board....

Nutrient removal using biosorption activated media: Preliminary biogeochemical assessment of an innovative stormwater infiltration basin

International Nuclear Information System (INIS)

O'Reilly, Andrew M.; Wanielista, Martin P.; Chang, Ni-Bin; Xuan, Zhemin; Harris, Willie G.

2012-01-01

Soil beneath a stormwater infiltration basin receiving runoff from a 23 ha predominantly residential watershed in north-central Florida, USA, was amended using biosorption activated media (BAM) to study the effectiveness of this technology in reducing inputs of nitrogen and phosphorus to groundwater. The functionalized soil amendment BAM consists of a 1.0:1.9:4.1 mixture (by volume) of tire crumb (to increase sorption capacity), silt and clay (to increase soil moisture retention), and sand (to promote sufficient infiltration), which was applied to develop an innovative stormwater infiltration basin utilizing nutrient reduction and flood control sub-basins. Comparison of nitrate/chloride (NO 3 − /Cl − ) ratios for the shallow groundwater indicates that prior to using BAM, NO 3 − concentrations were substantially influenced by nitrification or variations in NO 3 − input. In contrast, for the new basin utilizing BAM, NO 3 − /Cl − ratios indicate minor nitrification and NO 3 − losses with the exception of one summer sample that indicated a 45% loss. Biogeochemical indicators (denitrifier activity derived from real-time polymerase chain reaction and variations in major ions, nutrients, dissolved and soil gases, and stable isotopes) suggest that NO 3 − losses are primarily attributable to denitrification, whereas dissimilatory nitrate reduction to ammonium is a minor process. Denitrification was likely occurring intermittently in anoxic microsites in the unsaturated zone, which was enhanced by the increased soil moisture within the BAM layer and resultant reductions in surface/subsurface oxygen exchange that produced conditions conducive to increased denitrifier activity. Concentrations of total dissolved phosphorus and orthophosphate (PO 4 3− ) were reduced by more than 70% in unsaturated zone soil water, with the largest decreases in the BAM layer where sorption was the most likely mechanism for removal. Post-BAM PO 4 3− /Cl − ratios for shallow

Microbial controls on metal mobility under the low nutrient fluxes found throughout the subsurface

International Nuclear Information System (INIS)

Boult, Stephen; Hand, Victoria L.; Vaughan, David J.

2006-01-01

Laboratory simulations and field studies of the shallow subsurface have shown that microbes and their extracellular products can influence the mobility of toxic metals from waste disposal sites. Modelling the transport of contaminants in groundwater may, therefore, require the input of microbial ecology data in addition to geochemical data, thus increasing the costs and the uncertainty of predictions. However, whether microbial effects on contaminant mobility occur extensively in the natural subsurface is unknown because the conditions under which they have been observed hitherto are generally unrepresentative of the average subsurface environment. Here, we show that microbial activity affects the mobility of a toxic trace metal (Cu) under the relatively low nutrient fluxes that dominate subsurface systems. More particularly, we show that under these low nutrient conditions, microbes and microbial products can immobilize metal but may themselves be subject to subsequent mobilization, thus complicating the pattern of metal storage and release. Our results show that the capability of microbes in the subsurface to change both the capacity of porous media to store metal, and the behaviour of metal that is released, is not restricted to the well researched environments close to sites of waste disposal. We anticipate our simulations will be a starting point for generating input data for transport models, and specifying the mechanism of metal remobilisation in environments more representative of the subsurface generally

Do microorganism stoichiometric alterations affect carbon sequestration in paddy soil subjected to phosphorus input?

Science.gov (United States)

Zhang, ZhiJian; Li, HongYi; Hu, Jiao; Li, Xia; He, Qiang; Tian, GuangMing; Wang, Hang; Wang, ShunYao; Wang, Bei

2015-04-01

Ecological stoichiometry provides a powerful tool for integrating microbial biomass stoichiometry with ecosystem processes, opening far-reaching possibilities for linking microbial dynamics to soil carbon (C) metabolism in response to agricultural nutrient management. Despite its importance to crop yield, the role of phosphorus (P) with respect to ecological stoichiometry and soil C sequestration in paddy fields remains poorly understood, which limits our ability to predict nutrient-related soil C cycling. Here, we collected soil samples from a paddy field experiment after seven years of superphosphate application along a gradient of 0, 30, 60, and 90 (P-0 through P-90, respectively) kg.ha-1.yr-1 in order to evaluate the role of exogenous P on soil C sequestration through regulating microbial stoichiometry. P fertilization increased soil total organic C and labile organic C by 1-14% and 4-96%, respectively, while rice yield is a function of the activities of soil β-1,4-glucosidase (BG), acid phosphatase (AP), and the level of available soil P through a stepwise linear regression model. P input induced C limitation, as reflected by decreases in the ratios of C:P in soil and microbial biomass. An eco-enzymatic ratio indicating microbial investment in C vs. P acquisition, i.e., ln(BG): ln(AP), changed the ecological function of microbial C acquisition, and was stoichiometrically related to P input. This mechanism drove a shift in soil resource availability by increasing bacterial community richness and diversity, and stimulated soil C sequestration in the paddy field by enhancing C-degradation-related bacteria for the breakdown of plant-derived carbon sources. Therefore, the decline in the C:P stoichiometric ratio of soil microorganism biomass under P input was beneficial for soil C sequestration, which offered a "win-win" relationship for the maximum balance point between C sequestration and P availability for rice production in the face of climate change.

Microbial respiration, but not biomass, responded linearly to increasing light fraction organic matter input: Consequences for carbon sequestration.

Science.gov (United States)

Rui, Yichao; Murphy, Daniel V; Wang, Xiaoli; Hoyle, Frances C

2016-10-18

Rebuilding 'lost' soil carbon (C) is a priority in mitigating climate change and underpinning key soil functions that support ecosystem services. Microorganisms determine if fresh C input is converted into stable soil organic matter (SOM) or lost as CO 2 . Here we quantified if microbial biomass and respiration responded positively to addition of light fraction organic matter (LFOM, representing recent inputs of plant residue) in an infertile semi-arid agricultural soil. Field trial soil with different historical plant residue inputs [soil C content: control (tilled) = 9.6 t C ha -1 versus tilled + plant residue treatment (tilled + OM) = 18.0 t C ha -1 ] were incubated in the laboratory with a gradient of LFOM equivalent to 0 to 3.8 t C ha -1 (0 to 500% LFOM). Microbial biomass C significantly declined under increased rates of LFOM addition while microbial respiration increased linearly, leading to a decrease in the microbial C use efficiency. We hypothesise this was due to insufficient nutrients to form new microbial biomass as LFOM input increased the ratio of C to nitrogen, phosphorus and sulphur of soil. Increased CO 2 efflux but constrained microbial growth in response to LFOM input demonstrated the difficulty for C storage in this environment.

Nutrients, neurogenesis and brain ageing: From disease mechanisms to therapeutic opportunities.

Science.gov (United States)

Fidaleo, Marco; Cavallucci, Virve; Pani, Giovambattista

2017-10-01

Appreciation of the physiological relevance of mammalian adult neurogenesis has in recent years rapidly expanded from a phenomenon of homeostatic cell replacement and brain repair to the current view of a complex process involved in high order cognitive functions. In parallel, an array of endogenous or exogenous triggers of neurogenesis has also been identified, among which metabolic and nutritional cues have drawn significant attention. Converging evidence from animal and in vitro studies points to nutrient sensing and energy metabolism as major physiological determinants of neural stem cell fate, and modulators of the whole neurogenic process. While the cellular and molecular circuitries underlying metabolic regulation of neurogenesis are still incompletely understood, the key role of mitochondrial activity and dynamics, and the importance of autophagy have begun to be fully appreciated; moreover, nutrient-sensitive pathways and transducers such as the insulin-IGF cascade, the AMPK/mTOR axis and the transcription regulators CREB and Sirt-1 have been included, beside more established "developmental" signals like Notch and Wnt, in the molecular networks that dictate neural-stem-cell self-renewal, migration and differentiation in response to local and systemic inputs. Many of these nutrient-related cascades are deregulated in the contest of metabolic diseases and in ageing, and may contribute to impaired neurogenesis and thus to cognition defects observed in these conditions. Importantly, accumulating knowledge on the metabolic control of neurogenesis provides a theoretical framework for the trial of new or repurposed drugs capable of interfering with nutrient sensing as enhancers of neurogenesis in the context of neurodegeneration and brain senescence. Copyright © 2017 Elsevier Inc. All rights reserved.

A New Approach To Soil Sampling For Risk Assessment Of Nutrient Mobilisation.

Science.gov (United States)

Jonczyk, J. C.; Owen, G. J.; Snell, M. A.; Barber, N.; Benskin, C.; Reaney, S. M.; Haygarth, P.; Quinn, P. F.; Barker, P. A.; Aftab, A.; Burke, S.; Cleasby, W.; Surridge, B.; Perks, M. T.

2016-12-01

Traditionally, risks of nutrient and sediment losses from soils are assessed through a combination of field soil nutrient values on soil samples taken over the whole field and the proximity of the field to water courses. The field average nutrient concentration of the soil is used by farmers to determine fertiliser needs. These data are often used by scientists to assess the risk of nutrient losses to water course, though are not really `fit' for this purpose. The Eden Demonstration Test Catchment (http://www.edendtc.org.uk/) is a research project based in the River Eden catchment, NW UK, with the aim of cost effectively mitigating diffuse pollution from agriculture whilst maintaining agricultural productivity. Three instrumented focus catchments have been monitored since 2011, providing high resolution in-stream chemistry and ecological data, alongside some spatial data on soils, land use and nutrient inputs. An approach to mitigation was demonstrated in a small sub-catchment, where surface runoff was identified as the key drivers of nutrient losses, using a suite of runoff attenuation features. Other issues identified were management of hard- standings and soil compaction. A new approach for evaluating nutrient losses from soils is assessed in the Eden DTC project. The Sensitive Catchment Integrated Modelling and Prediction (SCIMAP) model is a risk-mapping framework designed to identify where in the landscape diffuse pollution is most likely to be originating (http://www.scimap.org.uk) and was used to look at the spatial pattern of erosion potential. The aim of this work was to assess if erosion potential identified through the model could be used to inform a new soil sampling strategy, to better assess risk of erosion and risk of transport of sediment-bound phosphorus. Soil samples were taken from areas with different erosion potential. The chemical analysis of these targeted samples are compared to those obtained using more traditional sampling approaches

The effects of CO2 and nutrient fertilisation on the growth and temperature response of the mangrove Avicennia germinans.

Science.gov (United States)

Reef, Ruth; Slot, Martijn; Motro, Uzi; Motro, Michal; Motro, Yoav; Adame, Maria F; Garcia, Milton; Aranda, Jorge; Lovelock, Catherine E; Winter, Klaus

2016-08-01

In order to understand plant responses to both the widespread phenomenon of increased nutrient inputs to coastal zones and the concurrent rise in atmospheric CO2 concentrations, CO2-nutrient interactions need to be considered. In addition to its potential stimulating effect on photosynthesis and growth, elevated CO2 affects the temperature response of photosynthesis. The scarcity of experiments testing how elevated CO2 affects the temperature response of tropical trees hinders our ability to model future primary productivity. In a glasshouse study, we examined the effects of elevated CO2 (800 ppm) and nutrient availability on seedlings of the widespread mangrove Avicennia germinans. We assessed photosynthetic performance, the temperature response of photosynthesis, seedling growth and biomass allocation. We found large synergistic gains in both growth (42 %) and photosynthesis (115 %) when seedlings grown under elevated CO2 were supplied with elevated nutrient concentrations relative to their ambient growing conditions. Growth was significantly enhanced under elevated CO2 only under high-nutrient conditions, mainly in above-ground tissues. Under low-nutrient conditions and elevated CO2, root volume was more than double that of seedlings grown under ambient CO2 levels. Elevated CO2 significantly increased the temperature optimum for photosynthesis by ca. 4 °C. Rising CO2 concentrations are likely to have a significant positive effect on the growth rate of A. germinans over the next century, especially in areas where nutrient availability is high.

The Nutrient Density of Snacks

Directory of Open Access Journals (Sweden)

Julie Hess BA

2017-03-01

Full Text Available Background: Although Americans receive almost a quarter of their daily energy from snacks, snacking remains a poorly defined and understood eating occasion. However, there is little dietary guidance about choosing snacks. Families, clinicians, and researchers need a comprehensive approach to assessing their nutritional value. Objective: To quantify and compare the nutrient density of commonly consumed snacks by their overall nutrient profiles using the Nutrient-Rich Foods (NRF Index 10.3. Methods: NRF Index scores were calculated for the top 3 selling products (based on 2014 market research data in different snack categories. These NRF scores were averaged to provide an overall nutrient-density score for each category. Results: Based on NRF scores, yogurt (55.3, milk (52.5, and fruit (30.1 emerged as the most nutrient-dense snacks. Ice cream (−4.4, pies and cakes (−11.1, and carbonated soft drinks (−17.2 emerged as the most nutrient-poor snacks. Conclusions: The NRF Index is a useful tool for assessing the overall nutritional value of snacks based on nutrients to limit and nutrients to encourage.

Soluble organic nutrient fluxes

Science.gov (United States)

Robert G. Qualls; Bruce L. Haines; Wayne Swank

2014-01-01

Our objectives in this study were (i) compare fluxes of the dissolved organic nutrients dissolved organic carbon (DOC), DON, and dissolved organic phosphorus (DOP) in a clearcut area and an adjacent mature reference area. (ii) determine whether concentrations of dissolved organic nutrients or inorganic nutrients were greater in clearcut areas than in reference areas,...

TART input manual

International Nuclear Information System (INIS)

Kimlinger, J.R.; Plechaty, E.F.

1982-01-01

The TART code is a Monte Carlo neutron/photon transport code that is only on the CRAY computer. All the input cards for the TART code are listed, and definitions for all input parameters are given. The execution and limitations of the code are described, and input for two sample problems are given

Locating inputs of freshwater to Lynch Cove, Hood Canal, Washington, using aerial infrared photography

Science.gov (United States)

Sheibley, Rich W.; Josberger, Edward G.; Chickadel, Chris

2010-01-01

The input of freshwater and associated nutrients into Lynch Cove and lower Hood Canal (fig. 1) from sources such as groundwater seeps, small streams, and ephemeral creeks may play a major role in the nutrient loading and hydrodynamics of this low dissolved-oxygen (hypoxic) system. These disbursed sources exhibit a high degree of spatial variability. However, few in-situ measurements of groundwater seepage rates and nutrient concentrations are available and thus may not represent adequately the large spatial variability of groundwater discharge in the area. As a result, our understanding of these processes and their effect on hypoxic conditions in Hood Canal is limited. To determine the spatial variability and relative intensity of these sources, the U.S. Geological Survey Washington Water Science Center collaborated with the University of Washington Applied Physics Laboratory to obtain thermal infrared (TIR) images of the nearshore and intertidal regions of Lynch Cove at or near low tide. In the summer, cool freshwater discharges from seeps and streams, flows across the exposed, sun-warmed beach, and out on the warm surface of the marine water. These temperature differences are readily apparent in aerial thermal infrared imagery that we acquired during the summers of 2008 and 2009. When combined with co-incident video camera images, these temperature differences allow identification of the location, the type, and the relative intensity of the sources.

Water-quality assessment of the Albermarle-Pamlico drainage basin, North Carolina and Virginia; a summary of selected trace element, nutrient, and pesticide data for bed sediments, 1969-90

Science.gov (United States)

Skrobialowski, S.C.

1996-01-01

Spatial distributions of metals and trace elements, nutrients, and pesticides and polychiorinated biphenyls (PCB's) in bed sediment were characterized using data collected from 1969 through 1990 and stored in the U.S. Geological Survey's National Water Data Storage and Retrieval (WATSTORE) system and the U.S. Environmental Protection Agency's Storage and Retrieval (STORET) system databases. Bed-sediment data from WATSTORE and STORET were combined to form a single database of 1,049 records representing 301 sites. Data were examined for concentrations of 16 metals and trace elements, 4 nutrients, 10 pesticides, and PCB's. Maximum bed-sediment concentrations were evaluated relative to sediment-quality guidelines developed by the National Oceanic and Atmospheric Administration, the Ontario Ministry of Environment and Energy, and the Virginia Department of Environmental Quality. Sites were not selected randomly; therefore, results should not be interpreted as representing average conditions. Many sites were located in or around lakes and reservoirs, urban areas, and areas where special investigations were conducted. Lakes and reservoirs function as effective sediment traps, and elevated concentrations of some constituents occurred at these sites. High concentrations of many metals and trace elements also occurred near urban areas where streams receive runoff or inputs from industrial, residential, and municipal activities. Elevated nutrient concentrations occurred near lakes, reservoirs, and the mouths of major rivers. The highest concentrations of arsenic, beryllium, chromium, iron. mercury, nickel, and selenium occurred in the Roanoke River Basin and may be a result of geologic formations or accumulations of bed sediment in lakes and reservoirs. The highest concentrations of cadmium, lead, and thallium were detected in the Chowan River Basin; copper and zinc were reported highest in the Neuse River Basin. Total phosphorus and total ammonia plus organic nitrogen

Floodplain trapping and cycling compared to streambank erosion of sediment and nutrients in an agricultural watershed

Science.gov (United States)

Gillespie, Jaimie; Noe, Gregory; Hupp, Cliff R.; Gellis, Allen; Schenk, Edward R.

2018-01-01

Floodplains and streambanks can positively and negatively influence downstream water quality through interacting geomorphic and biogeochemical processes. Few studies have measured those processes in agricultural watersheds. We measured inputs (floodplain sedimentation and dissolved inorganic loading), cycling (floodplain soil nitrogen [N] and phosphorus [P] mineralization), and losses (bank erosion) of sediment, N, and P longitudinally in stream reaches of Smith Creek, an agricultural watershed in the Valley and Ridge physiographic province. All study reaches were net depositional (floodplain deposition > bank erosion), had high N and P sedimentation and loading rates to the floodplain, high soil concentrations of N and P, and high rates of floodplain soil N and P mineralization. High sediment, N, and P inputs to floodplains are attributed to agricultural activity in the region. Rates of P mineralization were much greater than those measured in other studies of nontidal floodplains that used the same method. Floodplain connectivity and sediment deposition decreased longitudinally, contrary to patterns in most watersheds. The net trapping function of Smith Creek floodplains indicates a benefit to water quality. Further research is needed to determine if future decreases in floodplain deposition, continued bank erosion, and the potential for nitrate leaching from nutrient-enriched floodplain soils could pose a long-term source of sediment and nutrients to downstream rivers.

A methodology to quantify the aerobic and anaerobic sludge digestion performance for nutrient recycling in aquaponics

Directory of Open Access Journals (Sweden)

Delaide, B.

2018-01-01

Full Text Available Description of the subject. This research note presents a methodology to quantify the tilapia sludge digestion performance in aerobic and anaerobic reactors for aquaponic purpose. Both organic reduction and macro- and microelements mineralization performances were addressed. Objectives. To set up an appropriate methodology to quantify sludge digestion performance in aquaponics. To describe the methodology and illustrate it with some results as example. Method. Equations were adapted to quantify (1 the organic reduction performance in terms of chemical oxygen demand (COD and total suspended solids (TSS reduction, and (2 the nutrient recycling performance in terms of macro- and microelements mineralization. Results. The equations were applied to data obtained from experimental aerobic and anaerobic reactors as example. Reactors were able to remove at least 50% of the TSS and COD input. The nutrient mineralization was consistent with a 10 — 60% range for all macro- and micronutrients. Conclusions. The methodology provides explicit indicators on the sludge treatment performances for aquaponics. Treating aquaponic sludge onsite is promising to avoid sludge spillage, improve nutrient recycling and save water.

On-demand single-photon state generation via nonlinear absorption

International Nuclear Information System (INIS)

Hong Tao; Jack, Michael W.; Yamashita, Makoto

2004-01-01

We propose a method for producing on-demand single-photon states based on collision-induced exchanges of photons and unbalanced linear absorption between two single-mode light fields. These two effects result in an effective nonlinear absorption of photons in one of the modes, which can lead to single-photon states. A quantum nonlinear attenuator based on such a mechanism can absorb photons in a normal input light pulse and terminate the absorption at a single-photon state. Because the output light pulses containing single photons preserve the properties of the input pulses, we expect this method to be a means for building a highly controllable single-photon source

Sensitivity analysis of a pulse nutrient addition technique for estimating nutrient uptake in large streams

Science.gov (United States)

Laurence Lin; J.R. Webster

2012-01-01

The constant nutrient addition technique has been used extensively to measure nutrient uptake in streams. However, this technique is impractical for large streams, and the pulse nutrient addition (PNA) has been suggested as an alternative. We developed a computer model to simulate Monod kinetics nutrient uptake in large rivers and used this model to evaluate the...

L1 Adaptive Control Augmentation System with Application to the X-29 Lateral/Directional Dynamics: A Multi-Input Multi-Output Approach

Science.gov (United States)

Griffin, Brian Joseph; Burken, John J.; Xargay, Enric

2010-01-01

This paper presents an L(sub 1) adaptive control augmentation system design for multi-input multi-output nonlinear systems in the presence of unmatched uncertainties which may exhibit significant cross-coupling effects. A piecewise continuous adaptive law is adopted and extended for applicability to multi-input multi-output systems that explicitly compensates for dynamic cross-coupling. In addition, explicit use of high-fidelity actuator models are added to the L1 architecture to reduce uncertainties in the system. The L(sub 1) multi-input multi-output adaptive control architecture is applied to the X-29 lateral/directional dynamics and results are evaluated against a similar single-input single-output design approach.

Stakeholder co-development of farm level nutrient management software

Science.gov (United States)

Buckley, Cathal; Mechan, Sarah; Macken-Walsh, Aine; Heanue, Kevin

2013-04-01

Over the last number of decades intensification in the use nitrogen (N) and phosphorus (P) in agricultural production has lead to excessive accumulations of these nutrients in soils, groundwaters and surface water bodies (Sutton et al., 2011). According to the European Environment Agency (2012) despite some progress diffuse pollution from agriculture is still significant in more than 40% of Europe's water bodies in rivers and coastal waters, and in one third of the water bodies in lakes and transitional waters. Recently it was estimated that approximately 29% of monitored river channel length is polluted to some degree across the Republic of Ireland. Agricultural sources were suspected in 47 per cent of cases (EPA, 2012). Farm level management practices to reduce nutrient transfers from agricultural land to watercourses can be divided into source reduction and source interception approaches (Ribaudo et al., 2001). Source interception approaches involve capturing nutrients post mobilisation through policy instruments such as riparian buffer zones or wetlands. Conversely, the source reduction approach is preventative in nature and promotes strict management of nutrient at farm and field level to reduce risk of mobilisation in the first instance. This has the potential to deliver a double dividend of reduced nutrient loss to the wider ecosystem while maximising economic return to agricultural production at the field and farm levels. Adoption and use of nutrient management plans among farmers is far from the norm. This research engages key farmer and extension stakeholders to explore how current nutrient management planning software and outputs should be developed to make it more user friendly and usable in a practical way. An open innovation technology co-development approach was adopted to investigate what is demanded by the end users - farm advisors and farmers. Open innovation is a knowledge management strategy that uses the input of stakeholders to improve

Global nitrogen and phosphorus fertilizer use for agriculture production in the past half century: shifted hot spots and nutrient imbalance

Science.gov (United States)

Lu, Chaoqun; Tian, Hanqin

2017-03-01

In addition to enhancing agricultural productivity, synthetic nitrogen (N) and phosphorous (P) fertilizer application in croplands dramatically alters global nutrient budget, water quality, greenhouse gas balance, and their feedback to the climate system. However, due to the lack of geospatial fertilizer input data, current Earth system and land surface modeling studies have to ignore or use oversimplified data (e.g., static, spatially uniform fertilizer use) to characterize agricultural N and P input over decadal or century-long periods. In this study, we therefore develop global time series gridded data of annual synthetic N and P fertilizer use rate in agricultural lands, matched with HYDE 3.2 historical land use maps, at a resolution of 0.5° × 0.5° latitude-longitude during 1961-2013. Our data indicate N and P fertilizer use rates on per unit cropland area increased by approximately 8 times and 3 times, respectively, since the year 1961 when IFA (International Fertilizer Industry Association) and FAO (Food and Agricultural Organization) surveys of country-level fertilizer input became available. Considering cropland expansion, the increase in total fertilizer consumption is even larger. Hotspots of agricultural N fertilizer application shifted from the US and western Europe in the 1960s to eastern Asia in the early 21st century. P fertilizer input shows a similar pattern with an additional current hotspot in Brazil. We found a global increase in fertilizer N / P ratio by 0.8 g N g-1 P per decade (p human impacts on agroecosystem functions in the long run. Our data can serve as one of critical input drivers for regional and global models to assess the impacts of nutrient enrichment on climate system, water resources, food security, etc. Datasets available at doi:10.1594/PANGAEA.863323.

Nutrient removal using biosorption activated media: preliminary biogeochemical assessment of an innovative stormwater infiltration basin

Science.gov (United States)

O'Reilly, Andrew M.; Wanielista, Martin P.; Chang, Ni-Bin; Xuan, Zhemin; Harris, Willie G.

2012-01-01

Soil beneath a stormwater infiltration basin receiving runoff from a 22.7 ha predominantly residential watershed in central Florida, USA, was amended using biosorption activated media (BAM) to study the effectiveness of this technology in reducing inputs of nitrogen and phosphorus to groundwater. The functionalized soil amendment BAM consists of a 1.0:1.9:4.1 mixture (by volume) of tire crumb (to increase sorption capacity), silt and clay (to increase soil moisture retention), and sand (to promote sufficient infiltration), which was applied to develop a prototype stormwater infiltration basin utilizing nutrient reduction and flood control sub-basins. Comparison of nitrate/chloride (NO3-/Cl-) ratios for the shallow groundwater indicate that prior to using BAM, NO3- concentrations were substantially influenced by nitrification or variations in NO3- input. In contrast, for the prototype basin utilizing BAM, NO3-/Cl- ratios indicate minor nitrification and NO3- losses with the exception of one summer sample that indicated a 45% loss. Biogeochemical indicators (denitrifier activity derived from real-time polymerase chain reaction and variations in major ions, nutrients, dissolved and soil gases, and stable isotopes) suggest NO3- losses are primarily attributable to denitrification, whereas dissimilatory nitrate reduction to ammonium is a minor process. Denitrification was likely occurring intermittently in anoxic microsites in the unsaturated zone, which was enhanced by increased soil moisture within the BAM layer and resultant reductions in surface/subsurface oxygen exchange that produced conditions conducive to increased denitrifier activity. Concentrations of total dissolved phosphorus and orthophosphate (PO43-) were reduced by more than 70% in unsaturated zone soil water, with the largest decreases in the BAM layer where sorption was the most likely mechanism for removal. Post-BAM PO43-/Cl- ratios for shallow groundwater indicate predominantly minor increases and

Wastewater and Saltwater: Studying the Biogeochemistry and Microbial Activity Associated with Wastewater Inputs to San Francisco Bay

Science.gov (United States)

Challenor, T.; Menendez, A. D.; Damashek, J.; Francis, C. A.; Casciotti, K. L.

2014-12-01

Nitrification is the process of converting ammonium (NH­­4+) into nitrate (NO3-), and is a crucial step in removing nitrogen (N) from aquatic ecosystems. This process is governed by ammonia-oxidizing bacteria (AOB) and archaea (AOA) that utilize the ammonia monooxygenase gene (amoA). Studying the rates of nitrification and the abundances of ammonia-oxidizing microorganisms in south San Francisco Bay's Artesian Slough, which receives treated effluent from the massive San Jose-Santa Clara Regional Wastewater Facility, are important for understanding the cycling of nutrients in this small but complex estuary. Wastewater inputs can have negative environmental impacts, such as the release of nitrous oxide, a byproduct of nitrification and a powerful greenhouse gas. Nutrient inputs can also increase productivity and sometimes lead to oxygen depletion. Assessing the relative abundance and diversity of AOA and AOB, along with measuring nitrification rates gives vital information about the biology and biogeochemistry of this important N-cycling process. To calculate nitrification rates, water samples were spiked with 15N-labeled ammonium and incubated in triplicate for 24 hours. Four time-points were extracted across the incubation and the "denitrifier" method was used to measure the isotopic ratio of nitrate in the samples over time. In order to determine relative ratios of AOB to AOA, DNA was extracted from water samples and used in clade-specific amoA PCR assays. Nitrification rates were detectable in all locations sampled and were higher than in other regions of the bay, as were concentrations of nitrate and ammonium. Rates were highest in the regions of Artesian Slough most directly affected by wastewater effluent. AOB vastly outnumbered AOA, which is consistent with other studies showing that AOB prefer high nutrient environments. AOB diversity includes clades of Nitrosospira and Nitrosomonas prevalent in estuarine settings. Many of the sequenced genes are related

Upward nitrate transport by phytoplankton in oceanic waters: balancing nutrient budgets in oligotrophic seas

Directory of Open Access Journals (Sweden)

Tracy A. Villareal

2014-03-01

Full Text Available In oceanic subtropical gyres, primary producers are numerically dominated by small (1–5 µm diameter pro- and eukaryotic cells that primarily utilize recycled nutrients produced by rapid grazing turnover in a highly efficient microbial loop. Continuous losses of nitrogen (N to depth by sinking, either as single cells, aggregates or fecal pellets, are balanced by both nitrate inputs at the base of the euphotic zone and N2-fixation. This input of new N to balance export losses (the biological pump is a fundamental aspect of N cycling and central to understanding carbon fluxes in the ocean. In the Pacific Ocean, detailed N budgets at the time-series station HOT require upward transport of nitrate from the nutricline (80–100 m into the surface layer (∼0–40 m to balance productivity and export needs. However, concentration gradients are negligible and cannot support the fluxes. Physical processes can inject nitrate into the base of the euphotic zone, but the mechanisms for transporting this nitrate into the surface layer across many 10s of m in highly stratified systems are unknown. In these seas, vertical migration by the very largest (102–103 µm diameter phytoplankton is common as a survival strategy to obtain N from sub-euphotic zone depths. This vertical migration is driven by buoyancy changes rather than by flagellated movement and can provide upward N transport as nitrate (mM concentrations in the cells. However, the contribution of vertical migration to nitrate transport has been difficult to quantify over the required basin scales. In this study, we use towed optical systems and isotopic tracers to show that migrating diatom (Rhizosolenia mats are widespread in the N. Pacific Ocean from 140°W to 175°E and together with other migrating phytoplankton (Ethmodiscus, Halosphaera, Pyrocystis, and solitary Rhizosolenia can mediate time-averaged transport of N (235 µmol N m-2 d-1 equivalent to eddy nitrate injections (242 µmol NO3− m

Soil, water and nutrient conservation in mountain farming systems: case-study from the Sikkim Himalaya.

Science.gov (United States)

Sharma, E; Rai, S C; Sharma, R

2001-02-01

The Khanikhola watershed in Sikkim is agrarian with about 50% area under rain-fed agriculture representing the conditions of the middle mountains all over the Himalaya. The study was conducted to assess overland flow, soil loss and subsequent nutrient losses from different land uses in the watershed, and identify biotechnological inputs for management of mountain farming systems. Overland flow, soil and nutrient losses were very high from open agricultural (cropped) fields compared to other land uses, and more than 72% of nutrient losses were attributable to agriculture land use. Forests and large cardamom agroforestry conserved more soil compared to other land uses. Interventions, like cultivation of broom grass upon terrace risers, N2-fixing Albizia trees for maintenance of soil fertility and plantation of horticulture trees, have reduced the soil loss (by 22%). Soil and water conservation values (> 80%) of both large cardamom and broom grass were higher compared to other crops. Use of N2-fixing Albizia tree in large cardamom agroforestry and croplands contributed to soil fertility, and increased productivity and yield. Bio-composting of farm resources ensured increase in nutrient availability specially phosphorus in cropped areas. Agricultural practices in mountain areas should be strengthened with more agroforestry components, and cash crops like large cardamom and broom grass in agroforestry provide high economic return and are hydroecologically sustainable.

Data to support statistical modeling of instream nutrient load based on watershed attributes, southeastern United States, 2002

Science.gov (United States)

Hoos, Anne B.; Terziotti, Silvia; McMahon, Gerard; Savvas, Katerina; Tighe, Kirsten C.; Alkons-Wolinsky, Ruth

2008-01-01

This report presents and describes the digital datasets that characterize nutrient source inputs, environmental characteristics, and instream nutrient loads for the purpose of calibrating and applying a nutrient water-quality model for the southeastern United States for 2002. The model area includes all of the river basins draining to the south Atlantic and the eastern Gulf of Mexico, as well as the Tennessee River basin (referred to collectively as the SAGT area). The water-quality model SPARROW (SPAtially-Referenced Regression On Watershed attributes), developed by the U.S. Geological Survey, uses a regression equation to describe the relation between watershed attributes (predictors) and measured instream loads (response). Watershed attributes that are considered to describe nutrient input conditions and are tested in the SPARROW model for the SAGT area as source variables include atmospheric deposition, fertilizer application to farmland, manure from livestock production, permitted wastewater discharge, and land cover. Watershed and channel attributes that are considered to affect rates of nutrient transport from land to water and are tested in the SAGT SPARROW model as nutrient-transport variables include characteristics of soil, landform, climate, reach time of travel, and reservoir hydraulic loading. Datasets with estimates of each of these attributes for each individual reach or catchment in the reach-catchment network are presented in this report, along with descriptions of methods used to produce them. Measurements of nutrient water quality at stream monitoring sites from a combination of monitoring programs were used to develop observations of the response variable - mean annual nitrogen or phosphorus load - in the SPARROW regression equation. Instream load of nitrogen and phosphorus was estimated using bias-corrected log-linear regression models using the program Fluxmaster, which provides temporally detrended estimates of long-term mean load well

Bottom-up and Top-down Input Augment the Variability of Cortical Neurons

Science.gov (United States)

Nassi, Jonathan J.; Kreiman, Gabriel; Born, Richard T.

2016-01-01

SUMMARY Neurons in the cerebral cortex respond inconsistently to a repeated sensory stimulus, yet they underlie our stable sensory experiences. Although the nature of this variability is unknown, its ubiquity has encouraged the general view that each cell produces random spike patterns that noisily represent its response rate. In contrast, here we show that reversibly inactivating distant sources of either bottom-up or top-down input to cortical visual areas in the alert primate reduces both the spike train irregularity and the trial-to-trial variability of single neurons. A simple model in which a fraction of the pre-synaptic input is silenced can reproduce this reduction in variability, provided that there exist temporal correlations primarily within, but not between, excitatory and inhibitory input pools. A large component of the variability of cortical neurons may therefore arise from synchronous input produced by signals arriving from multiple sources. PMID:27427459

Nutrient acquisition strategies of mammalian cells.

Science.gov (United States)

Palm, Wilhelm; Thompson, Craig B

2017-06-07

Mammalian cells are surrounded by diverse nutrients, such as glucose, amino acids, various macromolecules and micronutrients, which they can import through transmembrane transporters and endolysosomal pathways. By using different nutrient sources, cells gain metabolic flexibility to survive periods of starvation. Quiescent cells take up sufficient nutrients to sustain homeostasis. However, proliferating cells depend on growth-factor-induced increases in nutrient uptake to support biomass formation. Here, we review cellular nutrient acquisition strategies and their regulation by growth factors and cell-intrinsic nutrient sensors. We also discuss how oncogenes and tumour suppressors promote nutrient uptake and thereby support the survival and growth of cancer cells.

Improving water management practices to reduce nutrient export from rice paddy fields.

Science.gov (United States)

Zhang, Zhi-Jian; Yao, Ju-Xiang; Wang, Zhao-De; Xu, Xin; Lin, Xian-Yong; Czapar, George F; Zhang, Jian-Ying

2011-01-01

Nitrogen (N) and phosphorus (P) loss from rice paddy fields represents a significant threat to water quality in China. In this project, three irrigation-drainage regimes were compared, including one conventional irrigation-drainage regime, i.e. continuous submergence regime (CSR), and two improved regimes, i.e. the alternating submergence-nonsubmergence regime (ASNR) and the zero-drainage irrigation technology (ZDIT), to seek cost-effective practices for reducing nutrient loss. The data from these comparisons showed that, excluding the nutrient input from irrigation, the net exports of total N and total P via surface field drainage ranged from -3.93 to 2.39 kg ha and 0.17 to 0.95 g ha(-1) under the CSR operation, respectively, while N loss was -2.46 to -2.23 kg ha(-1) and P export was -0.65 to 0.31 kg ha(-1) under the improved regimes. The intensity of P export was positively correlated to the rate of P application. Reducing the draining frequency or postponing the draining operation would shift the ecological role of the paddy field from a nutrient export source to an interception sink when ASNR or the zero-drainage water management was used. In addition, since the rice yields are being guaranteed at no additional cost, the improved irrigation-drainage operations would have economic as well as environmental benefits.

Integration of auditory and tactile inputs in musical meter perception.

Science.gov (United States)

Huang, Juan; Gamble, Darik; Sarnlertsophon, Kristine; Wang, Xiaoqin; Hsiao, Steven

2013-01-01

Musicians often say that they not only hear but also "feel" music. To explore the contribution of tactile information to "feeling" music, we investigated the degree that auditory and tactile inputs are integrated in humans performing a musical meter-recognition task. Subjects discriminated between two types of sequences, "duple" (march-like rhythms) and "triple" (waltz-like rhythms), presented in three conditions: (1) unimodal inputs (auditory or tactile alone); (2) various combinations of bimodal inputs, where sequences were distributed between the auditory and tactile channels such that a single channel did not produce coherent meter percepts; and (3) bimodal inputs where the two channels contained congruent or incongruent meter cues. We first show that meter is perceived similarly well (70-85 %) when tactile or auditory cues are presented alone. We next show in the bimodal experiments that auditory and tactile cues are integrated to produce coherent meter percepts. Performance is high (70-90 %) when all of the metrically important notes are assigned to one channel and is reduced to 60 % when half of these notes are assigned to one channel. When the important notes are presented simultaneously to both channels, congruent cues enhance meter recognition (90 %). Performance dropped dramatically when subjects were presented with incongruent auditory cues (10 %), as opposed to incongruent tactile cues (60 %), demonstrating that auditory input dominates meter perception. These observations support the notion that meter perception is a cross-modal percept with tactile inputs underlying the perception of "feeling" music.

Linking river nutrient concentrations to land use and rainfall in a paddy agriculture-urban area gradient watershed in southeast China.

Science.gov (United States)

Xia, Yongqiu; Ti, Chaopu; She, Dongli; Yan, Xiaoyuan

2016-10-01

The effects of land use and land-use changes on river nutrient concentrations are not well understood, especially in the watersheds of developing countries that have a mixed land use of rice paddy fields and developing urban surfaces. Here, we present a three-year study of a paddy agricultural-urban area gradient watershed in southeast China. The annual anthropogenic nitrogen (N) input from the agricultural region to the urban region was high, yet the results showed that the monthly nutrient concentrations in the river were low in the rainy seasons. The nutrient concentrations decreased continuously as the river water passed through the traditional agriculture region (TAR; paddy rice and wheat rotation) and increased substantially in the city region (CR). The traditional agricultural reference region exported most of the nutrient loads at high flows (>1mmd(-1)), the intensified agricultural region (IAR, aquaculture and poultry farming) exported most of the nutrient loads at moderate flows (between 0.5 and 1mmd(-1)), and the CR reference area exported most of the nutrient loads under low to moderate flows. We developed a statistical model to link variations in the nutrient concentrations to the proportion of land-use types and rainfall. The statistical results showed that impervious surfaces, which we interpret as a proxy for urban activities including sewage disposal, were the most important drivers of nutrient concentrations, whereas water surfaces accounted for a substantial proportion of the nutrient sinks. Therefore, to efficiently reduce water pollution, sewage from urban areas must be addressed as a priority, although wetland restoration could also achieve substantial pollutant removal. Copyright © 2016. Published by Elsevier B.V.

Secure communication based on multi-input multi-output chaotic system with large message amplitude

International Nuclear Information System (INIS)

Zheng, G.; Boutat, D.; Floquet, T.; Barbot, J.P.

2009-01-01

This paper deals with the problem of secure communication based on multi-input multi-output (MIMO) chaotic systems. Single input secure communication based on chaos can be easily extended to multiple ones by some combinations technologies, however all the combined inputs possess the same risk to be broken. In order to reduce this risk, a new secure communication scheme based on chaos with MIMO is discussed in this paper. Moreover, since the amplitude of messages in traditional schemes is limited because it would affect the quality of synchronization, the proposed scheme is also improved into an amplitude-independent one.

Estimates of long-term mean-annual nutrient loads considered for use in SPARROW models of the Midcontinental region of Canada and the United States, 2002 base year

Science.gov (United States)

Saad, David A.; Benoy, Glenn A.; Robertson, Dale M.

2018-05-11

Streamflow and nutrient concentration data needed to compute nitrogen and phosphorus loads were compiled from Federal, State, Provincial, and local agency databases and also from selected university databases. The nitrogen and phosphorus loads are necessary inputs to Spatially Referenced Regressions on Watershed Attributes (SPARROW) models. SPARROW models are a way to estimate the distribution, sources, and transport of nutrients in streams throughout the Midcontinental region of Canada and the United States. After screening the data, approximately 1,500 sites sampled by 34 agencies were identified as having suitable data for calculating the long-term mean-annual nutrient loads required for SPARROW model calibration. These final sites represent a wide range in watershed sizes, types of nutrient sources, and land-use and watershed characteristics in the Midcontinental region of Canada and the United States.

Supplementary High-Input Impedance Voltage-Mode Universal Biquadratic Filter Using DVCCs

Directory of Open Access Journals (Sweden)

Jitendra Mohan

2012-01-01

Full Text Available To further extend the existing knowledge on voltage-mode universal biquadratic filter, in this paper, a new biquadratic filter circuit with single input and multiple outputs is proposed, employing three differential voltage current conveyors (DVCCs, three resistors, and two grounded capacitors. The proposed circuit realizes all the standard filter functions, that is, high-pass, band-pass, low-pass, notch, and all-pass filters simultaneously. The circuit enjoys the feature of high-input impedance, orthogonal control of resonance angular frequency (o, and quality factor (Q via grounded resistor and the use of grounded capacitors which is ideal for IC implementation.

Development and use of a bioeconomic model for management of mussel fisheries under different nutrient regimes in the temperate estuary of the Limfjord, Denmark

DEFF Research Database (Denmark)

Timmermann, Karen; Dinesen, Grete E.; Markager, Stiig

2014-01-01

Coastal ecosystems worldwide are under pressure from human-induced nutrient inputs, fishing activities, mariculture, construction work, and climate change. Integrated management instruments handling one or more of these problems in combination with socioeconomic issues are therefore necessary...... to secure a sustainable use of resources. In the Limfjord, a temperate eutrophic estuary in Denmark, nutrient load reductions are necessary to fulfill EU regulations such as the Water Framework Directive (WFD). The expected outcome of these load reductions is an improved water quality, but also reduced...... reductions for mussel fishery as practiced today, as well as potential management options, to obtain an economically and ecologically sustainable mussel fishery. Model simulations clearly demonstrate a substantial decrease in mussel production after the nutrient load reductions necessary to obtain...

Road simulation for four-wheel vehicle whole input power spectral density

Science.gov (United States)

Wang, Jiangbo; Qiang, Baomin

2017-05-01

As the vibration of running vehicle mainly comes from road and influence vehicle ride performance. So the road roughness power spectral density simulation has great significance to analyze automobile suspension vibration system parameters and evaluate ride comfort. Firstly, this paper based on the mathematical model of road roughness power spectral density, established the integral white noise road random method. Then in the MATLAB/Simulink environment, according to the research method of automobile suspension frame from simple two degree of freedom single-wheel vehicle model to complex multiple degrees of freedom vehicle model, this paper built the simple single incentive input simulation model. Finally the spectrum matrix was used to build whole vehicle incentive input simulation model. This simulation method based on reliable and accurate mathematical theory and can be applied to the random road simulation of any specified spectral which provides pavement incentive model and foundation to vehicle ride performance research and vibration simulation.

Hypothalamic carnitine metabolism integrates nutrient and hormonal feedback to regulate energy homeostasis.

Science.gov (United States)

Stark, Romana; Reichenbach, Alex; Andrews, Zane B

2015-12-15

The maintenance of energy homeostasis requires the hypothalamic integration of nutrient feedback cues, such as glucose, fatty acids, amino acids, and metabolic hormones such as insulin, leptin and ghrelin. Although hypothalamic neurons are critical to maintain energy homeostasis research efforts have focused on feedback mechanisms in isolation, such as glucose alone, fatty acids alone or single hormones. However this seems rather too simplistic considering the range of nutrient and endocrine changes associated with different metabolic states, such as starvation (negative energy balance) or diet-induced obesity (positive energy balance). In order to understand how neurons integrate multiple nutrient or hormonal signals, we need to identify and examine potential intracellular convergence points or common molecular targets that have the ability to sense glucose, fatty acids, amino acids and hormones. In this review, we focus on the role of carnitine metabolism in neurons regulating energy homeostasis. Hypothalamic carnitine metabolism represents a novel means for neurons to facilitate and control both nutrient and hormonal feedback. In terms of nutrient regulation, carnitine metabolism regulates hypothalamic fatty acid sensing through the actions of CPT1 and has an underappreciated role in glucose sensing since carnitine metabolism also buffers mitochondrial matrix levels of acetyl-CoA, an allosteric inhibitor of pyruvate dehydrogenase and hence glucose metabolism. Studies also show that hypothalamic CPT1 activity also controls hormonal feedback. We hypothesis that hypothalamic carnitine metabolism represents a key molecular target that can concurrently integrate nutrient and hormonal information, which is critical to maintain energy homeostasis. We also suggest this is relevant to broader neuroendocrine research as it predicts that hormonal signaling in the brain varies depending on current nutrient status. Indeed, the metabolic action of ghrelin, leptin or insulin

Nutrient sequestration in Aquitaine lakes (SW France) limits nutrient flux to the coastal zone

Science.gov (United States)

Buquet, Damien; Anschutz, Pierre; Charbonnier, Céline; Rapin, Anne; Sinays, Rémy; Canredon, Axel; Bujan, Stéphane; Poirier, Dominique

2017-12-01

Oligotrophic coastal zones are disappearing from increased nutrient loading. The quantity of nutrients reaching the coast is determined not only by their original source (e.g. fertilizers used in agriculture, waste water discharges) and the land use, but also by the pathways through which nutrients are cycled from the source to the river mouth. In particular, lakes sequester nutrients and, hence, reduce downstream transfer of nutrients to coastal environments. Here, we quantify the impact of Aquitaine great lakes on the fluxes of dissolved macro-nutrients (N, P, Si) to the Bay of Biscay. For that, we have measured nutrient concentrations and fluxes in 2014 upstream and downstream lakes of Lacanau and Carcans-Hourtin, which belongs to the catchment of the Arcachon Bay, which is the largest coastal lagoon of the Bay of Biscay French coast. Data were compared to values obtained from the Leyre river, the main freshwater and nutrient source for the lagoon. Results show that processes in lakes greatly limit nutrient flux to the lagoon compared to fluxes from Leyre river, although the watershed is similar in terms of land cover. In lakes, phosphorus and silicon are trapped for long term in the sediment, silicon as amorphous biogenic silica and phosphorus as organic P and P associated with Fe-oxides. Nitrogen that enters lakes mostly as nitrate is used for primary production. N is mineralized in the sediment; a fraction diffuses as ammonium. N2 production through benthic denitrification extracts only 10% of dissolved inorganic nitrogen from the aquatic system. The main part is sequestered in organic-rich sediment that accumulates below 5 m depth in both lakes.

[An optical-fiber-sensor-based spectrophotometer for soil non-metallic nutrient determination].

Science.gov (United States)

He, Dong-xian; Hu, Juan-xiu; Lu, Shao-kun; He, Hou-yong

2012-01-01

In order to achieve rapid, convenient and efficient soil nutrient determination in soil testing and fertilizer recommendation, a portable optical-fiber-sensor-based spectrophotometer including immersed fiber sensor, flat field holographic concave grating, and diode array detector was developed for soil non-metallic nutrient determination. According to national standard of ultraviolet and visible spectrophotometer with JJG 178-2007, the wavelength accuracy and repeatability, baseline stability, transmittance accuracy and repeatability measured by the prototype instrument were satisfied with the national standard of III level; minimum spectral bandwidth, noise and excursion, and stray light were satisfied with the national standard of IV level. Significant linear relationships with slope of closing to 1 were found between the soil available nutrient contents including soil nitrate nitrogen, ammonia nitrogen, available phosphorus, available sulfur, available boron, and organic matter measured by the prototype instrument compared with that measured by two commercial single-beam-based and dual-beam-based spectrophotometers. No significant differences were revealed from the above comparison data. Therefore, the optical-fiber-sensor-based spectrophotometer can be used for rapid soil non-metallic nutrient determination with a high accuracy.

Input-output supervisor

International Nuclear Information System (INIS)

Dupuy, R.

1970-01-01

The input-output supervisor is the program which monitors the flow of informations between core storage and peripheral equipments of a computer. This work is composed of three parts: 1 - Study of a generalized input-output supervisor. With sample modifications it looks like most of input-output supervisors which are running now on computers. 2 - Application of this theory on a magnetic drum. 3 - Hardware requirement for time-sharing. (author) [fr

Implementasi Fuzzy Logic Controller untuk Mengatur Ph Nutrisi pada Sistem Hidroponik Nutrient Film Technique (NFT

Directory of Open Access Journals (Sweden)

Dian Pancawati

2016-07-01

Full Text Available One solution to solve limited agricultural land is applying hydroponics Nutrient Film Technique (NFT. The advantage of NFT is using water circulated as a growing medium in order to obtain water, nutrients and oxygen to accelerate the growth of plants with good results. The most important parameter is the pH of nutrients. This article discusses how to design an automatic nutritional pH control system by implementing the method of Fuzzy Logic Controller. The control system use Arduino Mega2560, Analog pH Meter Kit as input, and the solenoid valve as actuators. The best response of the implementation of Fuzzy Logic Controller with the system which has 25 rules. The response shows that the system has in 1200 millisecond rise time and the steady state in 5530 milliseconds to increase the pH. While to decrease the pH system has response of rise time at 2000 milliseconds and steady state at the time of 3000 milliseconds. The system is able to maintain the pH at 5.5, with the result of the growth of lettuce as high as 20 cm and seven leaves for 54 days.

TOPIC: a debugging code for torus geometry input data of Monte Carlo transport code

International Nuclear Information System (INIS)

Iida, Hiromasa; Kawasaki, Hiromitsu.

1979-06-01

TOPIC has been developed for debugging geometry input data of the Monte Carlo transport code. the code has the following features: (1) It debugs the geometry input data of not only MORSE-GG but also MORSE-I capable of treating torus geometry. (2) Its calculation results are shown in figures drawn by Plotter or COM, and the regions not defined or doubly defined are easily detected. (3) It finds a multitude of input data errors in a single run. (4) The input data required in this code are few, so that it is readily usable in a time sharing system of FACOM 230-60/75 computer. Example TOPIC calculations in design study of tokamak fusion reactors (JXFR, INTOR-J) are presented. (author)

Sr isotope characterization of atmospheric inputs to soils along a climate gradient of the Chilean Coastal Range

Science.gov (United States)

Oeser, Ralf; Schuessler, Jan A.; Floor, Geerke H.; von Blanckenburg, Friedhelm

2017-04-01

The rate and degree of rock weathering controls the release, distribution, and cycling of mineral nutrients at the Earth's surface, being essential for developing and sustaining of ecosystems. Climate plays an important role as water flow and temperature determine both the biological community and activity, and also set the speed of weathering. Because of this double control by climate, the impact of biological activity on rock weathering and the feedbacks between the geosphere and the biosphere under different climatic conditions are not well understood. We explore the impact of biota on rock weathering in the four EarthShape primary study areas which are situated along the Chilean Coastal Range, featuring an outstanding vegetation gradient controlled by climate, ranging over 2000 km from hyper-arid, to temperate, to humid conditions. The study sites are within 80 km of the Pacific coast and are located in granitic lithology. Moreover, the sites were unglaciated during the last glacial maximum. However, as substrates get depleted in mineral nutrients, ecosystems are increasingly nourished by atmospheric inputs, sources, such as solutes contained in rain, dust, and volcanic ash. We aim to quantify the primary nutrient inputs to the ecosystem from these different potential sources. Radiogenic strontium (Sr) isotope ratios are a powerful tool to trace chemical weathering, soil formation, as well as cation provenance and mobility [1]. We determined 87Sr/86Sr ratios on bulk bedrock, saprolite, and soil and performed sequential extractions of the the easily bioavailable soil phases up to 2 m depth on two soil depth profiles in each of the four study sites. Our first results from the La Campana study site indicate that the radiogenic Sr isotope ratios of saprolite samples decrease from 0.70571 (n = 4) at the base of the profile to lower values of 0.70520 (n = 4) at the top of the immobile saprolite, indicating increasing biotite weathering. 87Sr/86Sr increases in the

Main nutrient patterns and colorectal cancer risk in the European Prospective Investigation into Cancer and Nutrition study.

Science.gov (United States)

Moskal, Aurélie; Freisling, Heinz; Byrnes, Graham; Assi, Nada; Fahey, Michael T; Jenab, Mazda; Ferrari, Pietro; Tjønneland, Anne; Petersen, Kristina En; Dahm, Christina C; Hansen, Camilla Plambeck; Affret, Aurélie; Boutron-Ruault, Marie-Christine; Cadeau, Claire; Kühn, Tilman; Katzke, Verena; Iqbal, Khalid; Boeing, Heiner; Trichopoulou, Antonia; Bamia, Christina; Naska, Androniki; Masala, Giovanna; de Magistris, Maria Santucci; Sieri, Sabina; Tumino, Rosario; Sacerdote, Carlotta; Peeters, Petra H; Bueno-de-Mesquita, Bas H; Engeset, Dagrun; Licaj, Idlir; Skeie, Guri; Ardanaz, Eva; Buckland, Genevieve; Castaño, José M Huerta; Quirós, José R; Amiano, Pilar; Molina-Portillo, Elena; Winkvist, Anna; Myte, Robin; Ericson, Ulrika; Sonestedt, Emily; Perez-Cornago, Aurora; Wareham, Nick; Khaw, Kay-Tee; Huybrechts, Inge; Tsilidis, Konstantinos K; Ward, Heather; Gunter, Marc J; Slimani, Nadia

2016-11-22

Much of the current literature on diet-colorectal cancer (CRC) associations focused on studies of single foods/nutrients, whereas less is known about nutrient patterns. We investigated the association between major nutrient patterns and CRC risk in participants of the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Among 477 312 participants, intakes of 23 nutrients were estimated from validated dietary questionnaires. Using results from a previous principal component (PC) analysis, four major nutrient patterns were identified. Hazard ratios (HRs) and 95% confidence intervals (CIs) were computed for the association of each of the four patterns and CRC incidence using multivariate Cox proportional hazards models with adjustment for established CRC risk factors. During an average of 11 years of follow-up, 4517 incident cases of CRC were documented. A nutrient pattern characterised by high intakes of vitamins and minerals was inversely associated with CRC (HR per 1 s.d.=0.94, 95% CI: 0.92-0.98) as was a pattern characterised by total protein, riboflavin, phosphorus and calcium (HR (1 s.d.)=0.96, 95% CI: 0.93-0.99). The remaining two patterns were not significantly associated with CRC risk. Analysing nutrient patterns may improve our understanding of how groups of nutrients relate to CRC.

The role of the Everglades Mangrove Ecotone Region (EMER) in regulating nutrient cycling and wetland productivity in South Florida

Science.gov (United States)

Rivera-Monroy, Victor H.; Twilley, Robert R.; Davis, Stephen E.; Childers, Daniel L.; Simard, Marc; Chambers, Randolph; Jaffe, Rudolf; Boyer, Joseph N.; Rudnick, David T.; Zhang, Keqi; Castañeda-Moya, Edward; Ewe, Sharon M.L.; Price, Rene M.; Coronado-Molina, Carlos; Ross, Michael; Smith, Thomas J.; Michot, Beatrice; Meselhe, Ehab; Nuttle, William; Troxler, Tiffany G.; Noe, Gregory B.

2011-01-01

The authors summarize the main findings of the Florida Coastal Everglades Long-Term Ecological Research (FCE-LTER) program in the EMER, within the context of the Comprehensive Everglades Restoration Plan (CERP), to understand how regional processes, mediated by water flow, control population and ecosystem dynamics across the EMER landscape. Tree canopies with maximum height -1) in the calcareous marl substrate and long hydroperiod. Phosphorus limits the EMER and its freshwater watersheds due to the lack of terrigenous sediment input and the phosphorus-limited nature of the freshwater Everglades. Reduced freshwater delivery over the past 50 years, combined with Everglades compartmentalization and a 10 cm rise in coastal sea level, has led to the landward transgression (~1.5 km in 54 years) of the mangrove ecotone. Seasonal variation in freshwater input strongly controls the temporal variation of nitrogen and P exports (99%) from the Everglades to Florida Bay. Rapid changes in nutrient availability and vegetation distribution during the last 50 years show that future ecosystem restoration actions and land use decisions can exert a major influence, similar to sea level rise over the short term, on nutrient cycling and wetland productivity in the EMER.

Nutrient Management in Recirculating Hydroponic Culture

Science.gov (United States)

Bugbee, Bruce

2004-01-01

There is an increasing need to recirculate and reuse nutrient solutions in order to reduce environmental and economic costs. However, one of the weakest points in hydroponics is the lack of information on managing the nutrient solution. Many growers and research scientists dump out nutrient solutions and refill at weekly intervals. Other authors have recommended measuring the concentrations of individual nutrients in solution as a key to nutrient control and maintenance. Dumping and replacing solution is unnecessary. Monitoring ions in solution is not always necessary; in fact the rapid depletion of some nutrients often causes people to add toxic amounts of nutrients to the solution. Monitoring ions in solution is interesting, but it is not the key to effective maintenance.

Benthic biogeochemical cycling, nutrient stoichiometry, and carbon and nitrogen mass balances in a eutrophic freshwater bay

Science.gov (United States)

Klump, J.V.; Fitzgerald, S.A.; Waplesa, J.T.

2009-01-01

Green Bay, while representing only ,7% of the surface area and ??1.4% of the volume of Lake Michigan, contains one-third of the watershed of the lake, and receives approximately one-third of the total nutrient loading to the Lake Michigan basin, largely from the Fox River at the southern end of the bay. With a history of eutrophic conditions dating back nearly a century, the southern portion of the bay behaves as an efficient nutrient and sediment trap, sequestering much of the annual carbon and nitrogen input within sediments accumulating at up to 1 cm per year. Depositional fluxes of organic matter varied from ??0.1 mol C m-2 yr-1 to >10 mol C m-2 yr-1 and were both fairly uniform in stoichiometric composition and relatively labile. Estimates of benthic recycling derived from pore-water concentration gradients, whole-sediment incubation experiments, and deposition-burial models of early diagenesis yielded an estimated 40% of the carbon and 50% of the nitrogen recycled back into the overlying water. Remineralization was relatively rapid with ??50% of the carbon remineralized within <15 yr of deposition, and a mean residence time for metabolizable carbon and nitrogen in the sediments of 20 yr. On average, organic carbon regeneration occurred as 75% CO2, 15% CH4, and 10% dissolved organic carbon (DOC). Carbon and nitrogen budgets for the southern bay were based upon direct measurements of inputs and burial and upon estimates of export and production derived stoichiometrically from a coupled phosphorus budget. Loadings of organic carbon from rivers were ??3.7 mol m-2 yr-1, 80% in the form of DOC and 20% as particulate organic carbon. These inputs were lost through export to northern Green Bay and Lake Michigan (39%), through sediment burial (26%), and net CO2 release to the atmosphere (35%). Total carbon input, including new production, was 4.54 mol m-2 C yr-1, equivalent to ??10% of the gross annual primary production. Nitrogen budget terms were less well quantified

Response-based selection of barley cultivars and legume species for complementarity: Root morphology and exudation in relation to nutrient source.

Science.gov (United States)

Giles, Courtney D; Brown, Lawrie K; Adu, Michael O; Mezeli, Malika M; Sandral, Graeme A; Simpson, Richard J; Wendler, Renate; Shand, Charles A; Menezes-Blackburn, Daniel; Darch, Tegan; Stutter, Marc I; Lumsdon, David G; Zhang, Hao; Blackwell, Martin S A; Wearing, Catherine; Cooper, Patricia; Haygarth, Philip M; George, Timothy S

2017-02-01

Phosphorus (P) and nitrogen (N) use efficiency may be improved through increased biodiversity in agroecosystems. Phenotypic variation in plants' response to nutrient deficiency may influence positive complementarity in intercropping systems. A multicomponent screening approach was used to assess the influence of P supply and N source on the phenotypic plasticity of nutrient foraging traits in barley (H. vulgare L.) and legume species. Root morphology and exudation were determined in six plant nutrient treatments. A clear divergence in the response of barley and legumes to the nutrient treatments was observed. Root morphology varied most among legumes, whereas exudate citrate and phytase activity were most variable in barley. Changes in root morphology were minimized in plants provided with ammonium in comparison to nitrate but increased under P deficiency. Exudate phytase activity and pH varied with legume species, whereas citrate efflux, specific root length, and root diameter lengths were more variable among barley cultivars. Three legume species and four barley cultivars were identified as the most responsive to P deficiency and the most contrasting of the cultivars and species tested. Phenotypic response to nutrient availability may be a promising approach for the selection of plant combinations for minimal input cropping systems. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Input data for inferring species distributions in Kyphosidae world-wide

Directory of Open Access Journals (Sweden)

Steen Wilhelm Knudsen

2016-09-01

Full Text Available Input data files for inferring the relationship among the family Kyphosidae, as presented in (Knudsen and Clements, 2016 [1], is here provided together with resulting topologies, to allow the reader to explore the topologies in detail. The input data files comprise seven nexus-files with sequence alignments of mtDNA and nDNA markers for performing Bayesian analysis. A matrix of recoded character states inferred from the morphology examined in museum specimens representing Dichistiidae, Girellidae, Kyphosidae, Microcanthidae and Scorpididae, is also provided, and can be used for performing a parsimonious analysis to infer the relationship among these perciform families. The nucleotide input data files comprise both multiple and single representatives of the various species to allow for inference of the relationship among the species in Kyphosidae and between the families closely related to Kyphosidae. The ‘.xml’-files with various constrained relationships among the families potentially closely related to Kyphosidae are also provided to allow the reader to rerun and explore the results from the stepping-stone analysis. The resulting topologies are supplied in newick-file formats together with input data files for Bayesian analysis, together with ‘.xml’-files. Re-running the input data files in the appropriate software, will enable the reader to examine log-files and tree-files themselves. Keywords: Sea chub, Drummer, Kyphosus, Scorpis, Girella

Groundwater Inputs to Rivers: Hydrological, Biogeochemical and Ecological Effects Inferred by Environmental Isotopes

Energy Technology Data Exchange (ETDEWEB)

Stellato, L. [Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE), Seconda Universita degli Studi di Napoli, Caserta (Italy); Newman, B. D. [Isotope Hydrology Section, International Atomic Energy Agency, Vienna (Austria)

2013-05-15

In an effort to improve river management, numerous studies over the past two decades have supported the concept that river water and groundwater need to be considered together, as part of a hydrologic continuum. In particular, studies of the interface between surface water and groundwater (the hyporheic zone) have seen the tight collaboration of catchment hydrologists and stream ecologists in order to elucidate processes affecting stream functioning. Groundwater and surface waters interact at different spatial and temporal scales depending on system hydrology and geomorphology, which in turn influence nutrient cycling and in-stream ecology in relation to climatic, geologic, biotic and anthropogenic factors. In this paper, groundwater inputs to rivers are explored from two different and complementary perspectives: the hydrogeological, describing the generally acknowledged mechanisms of streamflow generation and the main factors controlling stream-aquifer interactions, and the ecologic, describing the processes occurring at the hyporheical and the riparian zones and their possible effects on stream functioning and on nutrient cycling, also taking into consideration the impact of human activities. Groundwater inflows to rivers can be important controls on hot moment/hot spot type biogeochemical behaviors. A description of the common methods used to assess these processes is provided emphasizing tracer methods (including physical, chemical and isotopic). In particular, naturally occurring isotopes are useful tools to identify stream discharge components, biogeochemical processes involved in nutrient cycling (such as N and P dynamics), nutrient sources and transport to rivers, and subsurface storage zones and residence times of hyporheic water. Several studies which have employed isotope techniques to clarify the processes occurring when groundwater enters the river,are reported in this chapter, with a view to highlighting both the advantages and limitations of these

Ecosystem and physiological scales of microbial responses to nutrients in a detritus-based stream: results of a 5-year continuous enrichment

Science.gov (United States)

Keller Suberkropp; Vladislav Gulis; Amy D. Rosemond; Jonathan Benstead

2010-01-01

Our study examined the response of leaf detritus–associated microorganisms (both bacteria and fungi) to a 5-yr continuous nutrient enrichment of a forested headwater stream. Leaf litter dominates detritus inputs to such streams and, on a system wide scale, serves as the key substrate for microbial colonization. We determined physiological responses as microbial biomass...

Yield Gap, Indigenous Nutrient Supply and Nutrient Use Efficiency for Maize in China

Science.gov (United States)

Xu, Xinpeng; Liu, Xiaoyan; He, Ping; Johnston, Adrian M.; Zhao, Shicheng; Qiu, Shaojun; Zhou, Wei

2015-01-01

Great achievements have been attained in agricultural production of China, while there are still many difficulties and challenges ahead that call for put more efforts to overcome to guarantee food security and protect environment simultaneously. Analyzing yield gap and nutrient use efficiency will help develop and inform agricultural policies and strategies to increase grain yield. On-farm datasets from 2001 to 2012 with 1,971 field experiments for maize (Zea mays L.) were collected in four maize agro-ecological regions of China, and the optimal management (OPT), farmers’ practice (FP), a series of nutrient omission treatments were used to analyze yield gap, nutrient use efficiency and indigenous nutrient supply by adopting meta-analysis and ANOVA analysis. Across all sites, the average yield gap between OPT and FP was 0.7 t ha-1, the yield response to nitrogen (N), phosphorus (P), and potassium (K) were 1.8, 1.0, and 1.2 t ha-1, respectively. The soil indigenous nutrient supply of N, P, and K averaged 139.9, 33.7, and 127.5 kg ha-1, respectively. As compared to FP, the average recovery efficiency (RE) of N, P, and K with OPT increased by percentage point of 12.2, 5.5, and 6.5, respectively. This study indicated that there would be considerable potential to further improve yield and nutrient use efficiency in China, and will help develop and inform agricultural policies and strategies, while some management measures such as soil, plant and nutrient are necessary and integrate with advanced knowledge and technologies. PMID:26484543

Yield Gap, Indigenous Nutrient Supply and Nutrient Use Efficiency for Maize in China.

Directory of Open Access Journals (Sweden)

Xinpeng Xu

Full Text Available Great achievements have been attained in agricultural production of China, while there are still many difficulties and challenges ahead that call for put more efforts to overcome to guarantee food security and protect environment simultaneously. Analyzing yield gap and nutrient use efficiency will help develop and inform agricultural policies and strategies to increase grain yield. On-farm datasets from 2001 to 2012 with 1,971 field experiments for maize (Zea mays L. were collected in four maize agro-ecological regions of China, and the optimal management (OPT, farmers' practice (FP, a series of nutrient omission treatments were used to analyze yield gap, nutrient use efficiency and indigenous nutrient supply by adopting meta-analysis and ANOVA analysis. Across all sites, the average yield gap between OPT and FP was 0.7 t ha-1, the yield response to nitrogen (N, phosphorus (P, and potassium (K were 1.8, 1.0, and 1.2 t ha-1, respectively. The soil indigenous nutrient supply of N, P, and K averaged 139.9, 33.7, and 127.5 kg ha-1, respectively. As compared to FP, the average recovery efficiency (RE of N, P, and K with OPT increased by percentage point of 12.2, 5.5, and 6.5, respectively. This study indicated that there would be considerable potential to further improve yield and nutrient use efficiency in China, and will help develop and inform agricultural policies and strategies, while some management measures such as soil, plant and nutrient are necessary and integrate with advanced knowledge and technologies.

Yield Gap, Indigenous Nutrient Supply and Nutrient Use Efficiency for Maize in China.

Science.gov (United States)

Xu, Xinpeng; Liu, Xiaoyan; He, Ping; Johnston, Adrian M; Zhao, Shicheng; Qiu, Shaojun; Zhou, Wei

2015-01-01

Great achievements have been attained in agricultural production of China, while there are still many difficulties and challenges ahead that call for put more efforts to overcome to guarantee food security and protect environment simultaneously. Analyzing yield gap and nutrient use efficiency will help develop and inform agricultural policies and strategies to increase grain yield. On-farm datasets from 2001 to 2012 with 1,971 field experiments for maize (Zea mays L.) were collected in four maize agro-ecological regions of China, and the optimal management (OPT), farmers' practice (FP), a series of nutrient omission treatments were used to analyze yield gap, nutrient use efficiency and indigenous nutrient supply by adopting meta-analysis and ANOVA analysis. Across all sites, the average yield gap between OPT and FP was 0.7 t ha-1, the yield response to nitrogen (N), phosphorus (P), and potassium (K) were 1.8, 1.0, and 1.2 t ha-1, respectively. The soil indigenous nutrient supply of N, P, and K averaged 139.9, 33.7, and 127.5 kg ha-1, respectively. As compared to FP, the average recovery efficiency (RE) of N, P, and K with OPT increased by percentage point of 12.2, 5.5, and 6.5, respectively. This study indicated that there would be considerable potential to further improve yield and nutrient use efficiency in China, and will help develop and inform agricultural policies and strategies, while some management measures such as soil, plant and nutrient are necessary and integrate with advanced knowledge and technologies.

Single chip camera active pixel sensor

Science.gov (United States)

Shaw, Timothy (Inventor); Pain, Bedabrata (Inventor); Olson, Brita (Inventor); Nixon, Robert H. (Inventor); Fossum, Eric R. (Inventor); Panicacci, Roger A. (Inventor); Mansoorian, Barmak (Inventor)

2003-01-01

A totally digital single chip camera includes communications to operate most of its structure in serial communication mode. The digital single chip camera include a D/A converter for converting an input digital word into an analog reference signal. The chip includes all of the necessary circuitry for operating the chip using a single pin.

A model for growth of a single fungal hypha based on well-mixed tanks in series: simulation of nutrient and vesicle transport in aerial reproductive hyphae.

Science.gov (United States)

Balmant, Wellington; Sugai-Guérios, Maura Harumi; Coradin, Juliana Hey; Krieger, Nadia; Furigo Junior, Agenor; Mitchell, David Alexander

2015-01-01

Current models that describe the extension of fungal hyphae and development of a mycelium either do not describe the role of vesicles in hyphal extension or do not correctly describe the experimentally observed profile for distribution of vesicles along the hypha. The present work uses the n-tanks-in-series approach to develop a model for hyphal extension that describes the intracellular transport of nutrient to a sub-apical zone where vesicles are formed and then transported to the tip, where tip extension occurs. The model was calibrated using experimental data from the literature for the extension of reproductive aerial hyphae of three different fungi, and was able to describe different profiles involving acceleration and deceleration of the extension rate. A sensitivity analysis showed that the supply of nutrient to the sub-apical vesicle-producing zone is a key factor influencing the rate of extension of the hypha. Although this model was used to describe the extension of a single reproductive aerial hypha, the use of the n-tanks-in-series approach to representing the hypha means that the model has the flexibility to be extended to describe the growth of other types of hyphae and the branching of hyphae to form a complete mycelium.

The role of diatom nanostructures in biasing diffusion to improve uptake in a patchy nutrient environment.

Directory of Open Access Journals (Sweden)

James G Mitchell

Full Text Available BACKGROUND: Diatoms are important single-celled autotrophs that dominate most lit aquatic environments and are distinguished by surficial frustules with intricate designs of unknown function. PRINCIPAL FINDINGS: We show that some frustule designs constrain diffusion to positively alter nutrient uptake. In nutrient gradients of 4 to 160 times over <5 cm, the screened-chambered morphology of Coscincodiscus sp. biases the nutrient diffusion towards the cell by at least 3.8 times the diffusion to the seawater. In contrast, the open-chambers of Thalassiosira eccentrica produce at least a 1.3 times diffusion advantage to the membrane over Coscincodiscus sp. when nutrients are homogeneous. SIGNIFICANCE: Diffusion constraint explains the success of particular diatom species at given times and the overall success of diatoms. The results help answer the unresolved question of how adjacent microplankton compete. Furthermore, diffusion constraint by supramembrane nanostructures to alter molecular diffusion suggests that microbes compete via supramembrane topology, a competitive mechanism not considered by the standard smooth-surface equations used for nutrient uptake nor in microbial ecology and cell physiology.

Nutrient imbalance in Norway spruce

International Nuclear Information System (INIS)

Thelin, Gunnar

2000-11-01

The studies presented in my thesis indicate that growing Norway spruce in monoculture does not constitute sustainable forest management in a high N and S deposition environment, such as in southern Sweden. The combination of N-induced high growth rates and leaching due to soil acidification causes soil reserves of nutrients to decrease. This will increase the risk of nutrient imbalance within the trees when nutrient demands are not met. The development of nutrient imbalance in Scania, southern Sweden, was shown as negative trends in needle and soil nutrient status from the mid-80s to the present in Norway spruce and Scots pine stands. This imbalance appears to be connected to high levels of N and S deposition. Clear negative effects on tree vitality were found when using a new branch development method. Today, growth and vitality seems to be limited by K, rather than N, in spruce stands older than 40 years. However, younger stands appear to be able to absorb the deposited N without negative effects on growth and vitality. When investigating effects of nutrient stress on tree vitality, indicators such as branch length and shoot multiplication rate, which include effects accumulated over several years, are suitable. Countermeasures are needed in order to maintain the forest production at a high level. Positive effects on tree nutrient status after vitality fertilization (N-free fertilization) was shown in two micronutrient deficient stands in south-central Sweden. In addition, tree vitality was positively affected after the application of a site-adapted fertilizer to the canopy. Site-adaption of fertilizers will most likely improve the possibilities of a positive response on tree growth and vitality in declining stands. In a survey of Norway spruce in mixtures with beech, birch, or oak compared to monocultures it was shown that spruce nutrient status was higher in mixtures with deciduous species than in monocultures. By using mixed-species stands the need for

Nutrient imbalance in Norway spruce

Energy Technology Data Exchange (ETDEWEB)

Thelin, Gunnar

2000-11-01

The studies presented in my thesis indicate that growing Norway spruce in monoculture does not constitute sustainable forest management in a high N and S deposition environment, such as in southern Sweden. The combination of N-induced high growth rates and leaching due to soil acidification causes soil reserves of nutrients to decrease. This will increase the risk of nutrient imbalance within the trees when nutrient demands are not met. The development of nutrient imbalance in Scania, southern Sweden, was shown as negative trends in needle and soil nutrient status from the mid-80s to the present in Norway spruce and Scots pine stands. This imbalance appears to be connected to high levels of N and S deposition. Clear negative effects on tree vitality were found when using a new branch development method. Today, growth and vitality seems to be limited by K, rather than N, in spruce stands older than 40 years. However, younger stands appear to be able to absorb the deposited N without negative effects on growth and vitality. When investigating effects of nutrient stress on tree vitality, indicators such as branch length and shoot multiplication rate, which include effects accumulated over several years, are suitable. Countermeasures are needed in order to maintain the forest production at a high level. Positive effects on tree nutrient status after vitality fertilization (N-free fertilization) was shown in two micronutrient deficient stands in south-central Sweden. In addition, tree vitality was positively affected after the application of a site-adapted fertilizer to the canopy. Site-adaption of fertilizers will most likely improve the possibilities of a positive response on tree growth and vitality in declining stands. In a survey of Norway spruce in mixtures with beech, birch, or oak compared to monocultures it was shown that spruce nutrient status was higher in mixtures with deciduous species than in monocultures. By using mixed-species stands the need for

USA Nutrient managment forecasting via the "Fertilizer Forecaster": linking surface runnof, nutrient application and ecohydrology.

Science.gov (United States)

Drohan, Patrick; Buda, Anthony; Kleinman, Peter; Miller, Douglas; Lin, Henry; Beegle, Douglas; Knight, Paul

2017-04-01

USA and state nutrient management planning offers strategic guidance that strives to educate farmers and those involved in nutrient management to make wise management decisions. A goal of such programs is to manage hotspots of water quality degradation that threaten human and ecosystem health, water and food security. The guidance provided by nutrient management plans does not provide the day-to-day support necessary to make operational decisions, particularly when and where to apply nutrients over the short term. These short-term decisions on when and where to apply nutrients often make the difference between whether the nutrients impact water quality or are efficiently utilized by crops. Infiltrating rainfall events occurring shortly after broadcast nutrient applications are beneficial, given they will wash soluble nutrients into the soil where they are used by crops. Rainfall events that generate runoff shortly after nutrients are broadcast may wash off applied nutrients, and produce substantial nutrient losses from that site. We are developing a model and data based support tool for nutrient management, the Fertilizer Forecaster, which identifies the relative probability of runoff or infiltrating events in Pennsylvania (PA) landscapes in order to improve water quality. This tool will support field specific decisions by farmers and land managers on when and where to apply fertilizers and manures over 24, 48 and 72 hour periods. Our objectives are to: (1) monitor agricultural hillslopes in watersheds representing four of the five Physiographic Provinces of the Chesapeake Bay basin; (2) validate a high resolution mapping model that identifies soils prone to runoff; (3) develop an empirically based approach to relate state-of-the-art weather forecast variables to site-specific rainfall infiltration or runoff occurrence; (4) test the empirical forecasting model against alternative approaches to forecasting runoff occurrence; and (5) recruit farmers from the four

Deciphering relationships between in-stream travel times, nutrient concentrations, and uptake through analysis of hysteretic and non-hysteretic kinetic behavior

Science.gov (United States)

Covino, T. P.; Bowden, W. B.; Gooseff, M. N.; Wollheim, W. M.; McGlynn, B. L.; Whittinghill, K. A.; Wlostowski, A. N.; Herstand, M. R.

2012-12-01

Understanding the relationship between solute travel time, concentration, and nutrient uptake remains a central question in watershed hydrology and biogeochemistry. Theoretical understanding predicts that nutrient uptake should increase as in-stream solute travel time lengthens and/or as concentration increases; however, results from field-based studies have been contradictory. We used a newly developed approach, Tracer Additions for Spiraling Curve Characterization (TASCC), to investigate relationships between solute travel time, nutrient concentration, and nutrient uptake across a range of stream types. This approach allows us to quantify in-stream nutrient uptake across a range of travel times and nutrient concentrations using single instantaneous injections (slugs) of conservative and non-conservative tracers. In some systems we observed counter-clockwise hysteresis loops in the relationship between nutrient uptake and concentration. Greater nutrient uptake on the falling limb of tracer breakthrough curves indicates stronger uptake for a given concentration at longer travel times. However, in other systems we did not observe hysteresis in these relationships. Lack of hysteresis indicates that nutrient uptake kinetics were not influenced by travel time travel time. Here we investigate the potential roles of travel time and in-stream flowpaths that could be responsible for hysteretic behavior.

Developmental Strategy For Effective Sampling To Detect Possible Nutrient Fluxes In Oligotrophic Coastal Reef Waters In The Caribbean

Science.gov (United States)

Mendoza, W. G.; Corredor, J. E.; Ko, D.; Zika, R. G.; Mooers, C. N.

2008-05-01

The increasing effort to develop the coastal ocean observing system (COOS) in various institutions has gained momentum due to its high value to climate, environmental, economic, and health issues. The stress contributed by nutrients to the coral reef ecosystem is among many problems that are targeted to be resolved using this system. Traditional nutrient sampling has been inadequate to resolve issues on episodic nutrient fluxes in reef regions due to temporal and spatial variability. This paper illustrates sampling strategy using the COOS information to identify areas that need critical investigation. The area investigated is within the Puerto Rico subdomain (60-70oW, 15-20oN), and Caribbean Time Series (CaTS), World Ocean Circulation Experiment (WOCE), Intra-America Sea (IAS) ocean nowcast/forecast system (IASNFS), and other COOS-related online datasets are utilized. Nutrient profile results indicate nitrate is undetectable in the upper 50 m apparently due to high biological consumption. Nutrients are delivered in Puerto Rico particularly in the CaTS station either via a meridional jet formed from opposing cyclonic and anticyclonic eddies or wind-driven upwelling. The strong vertical fluctuation in the upper 50 m demonstrates a high anomaly in temperature and salinity and a strong cross correlation signal. High chlorophyll a concentration corresponding to seasonal high nutrient influx coincides with higher precipitation accumulation rates and apparent riverine input from the Amazon and Orinoco Rivers during summer (August) than during winter (February) seasons. Non-detectability of nutrients in the upper 50 m is a reflection of poor sampling frequency or the absence of a highly sensitive nutrient analysis method to capture episodic events. Thus, this paper was able to determine the range of depths and concentrations that need to be critically investigated to determine nutrient fluxes, nutrient sources, and climatological factors that can affect nutrient delivery

Seasonal evolution of the nutrient pattern on Biscay Bay continental shelf over the years 1999-2000

Directory of Open Access Journals (Sweden)

Sophie Loyer

2006-03-01

Full Text Available The French Atlantic shelf is subjected to strong anthropic influences (urban, industrial and agricultural discharges of two main rivers (Loire and Gironde. The extension and consequences of these continental loadings for the nutrient and chlorophyll distribution have never been studied before on the Bay of Biscay continental shelf as a whole. We present the first synoptic view of the nutrient distribution and evolution on the French Atlantic shelf. Nutrient concentrations of the surface layer were studied during four cruises in April, June, September 1999 and March 2000. Until June, the freshwater inputs induce a nitrate gradient from river mouths to offshore waters in the vicinity of the 100 m isobath. The Redfield’s ratio study highlights the nitrate excess in river loadings. The early spring situation is characterised by high N:P ratios in front of the two estuaries and by a potential Si-limitation in the northern part. Nitrate removal continues in spite of the P-limitation and the increase in silicate concentrations during summer supposes high regeneration processes. At the end of summer, the water column is thermally stratified and the surface mixed layer is totally depleted in nitrate.

Competition for nutrients and light: testing advances in resource competition with a natural phytoplankton community.

Science.gov (United States)

Burson, Amanda; Stomp, Maayke; Greenwell, Emma; Grosse, Julia; Huisman, Jef

2018-05-01

A key challenge in ecology is to understand how nutrients and light affect the biodiversity and community structure of phytoplankton and plant communities. According to resource competition models, ratios of limiting nutrients are major determinants of species composition. At high nutrient levels, however, species interactions may shift to competition for light, which might make nutrient ratios less relevant. The "nutrient-load hypothesis" merges these two perspectives, by extending the classic model of competition for two nutrients to include competition for light. Here, we test five key predictions of the nutrient-load hypothesis using multispecies competition experiments. A marine phytoplankton community sampled from the North Sea was inoculated in laboratory chemostats provided with different nitrogen (N) and phosphorus (P) loads to induce either single resource limitation or co-limitation of N, P, and light. Four of the five predictions were validated by the experiments. In particular, different resource limitations favored the dominance of different species. Increasing nutrient loads caused changes in phytoplankton species composition, even if the N:P ratio of the nutrient loads remained constant, by shifting the species interactions from competition for nutrients to competition for light. In all treatments, small species became dominant whereas larger species were competitively excluded, supporting the common view that small cell size provides a competitive advantage under resource-limited conditions. Contrary to expectation, all treatments led to coexistence of diatoms, cyanobacteria and green algae, resulting in a higher diversity of species than predicted by theory. Because the coexisting species comprised three phyla with different photosynthetic pigments, we speculate that niche differentiation in the light spectrum might play a role. Our results show that mechanistic resource competition models that integrate nutrient-based and light-based approaches

ColloInputGenerator

DEFF Research Database (Denmark)

2013-01-01

This is a very simple program to help you put together input files for use in Gries' (2007) R-based collostruction analysis program. It basically puts together a text file with a frequency list of lexemes in the construction and inserts a column where you can add the corpus frequencies. It requires...... it as input for basic collexeme collostructional analysis (Stefanowitsch & Gries 2003) in Gries' (2007) program. ColloInputGenerator is, in its current state, based on programming commands introduced in Gries (2009). Projected updates: Generation of complete work-ready frequency lists....

An approach for coupled-code multiphysics core simulations from a common input

International Nuclear Information System (INIS)

Schmidt, Rodney; Belcourt, Kenneth; Hooper, Russell; Pawlowski, Roger; Clarno, Kevin; Simunovic, Srdjan; Slattery, Stuart; Turner, John; Palmtag, Scott

2015-01-01

Highlights: • We describe an approach for coupled-code multiphysics reactor core simulations. • The approach can enable tight coupling of distinct physics codes with a common input. • Multi-code multiphysics coupling and parallel data transfer issues are explained. • The common input approach and how the information is processed is described. • Capabilities are demonstrated on an eigenvalue and power distribution calculation. - Abstract: This paper describes an approach for coupled-code multiphysics reactor core simulations that is being developed by the Virtual Environment for Reactor Applications (VERA) project in the Consortium for Advanced Simulation of Light-Water Reactors (CASL). In this approach a user creates a single problem description, called the “VERAIn” common input file, to define and setup the desired coupled-code reactor core simulation. A preprocessing step accepts the VERAIn file and generates a set of fully consistent input files for the different physics codes being coupled. The problem is then solved using a single-executable coupled-code simulation tool applicable to the problem, which is built using VERA infrastructure software tools and the set of physics codes required for the problem of interest. The approach is demonstrated by performing an eigenvalue and power distribution calculation of a typical three-dimensional 17 × 17 assembly with thermal–hydraulic and fuel temperature feedback. All neutronics aspects of the problem (cross-section calculation, neutron transport, power release) are solved using the Insilico code suite and are fully coupled to a thermal–hydraulic analysis calculated by the Cobra-TF (CTF) code. The single-executable coupled-code (Insilico-CTF) simulation tool is created using several VERA tools, including LIME (Lightweight Integrating Multiphysics Environment for coupling codes), DTK (Data Transfer Kit), Trilinos, and TriBITS. Parallel calculations are performed on the Titan supercomputer at Oak

Response of dissolved carbon and nitrogen concentrations to moderate nutrient additions in a tropical montane forest of south Ecuador

Science.gov (United States)

Velescu, Andre; Valarezo, Carlos; Wilcke, Wolfgang

2016-05-01

In the past two decades, the tropical montane rain forests in south Ecuador experienced increasing deposition of reactive nitrogen mainly originating from Amazonian forest fires, while Saharan dust inputs episodically increased deposition of base metals. Increasing air temperature and unevenly distributed rainfall have allowed for longer dry spells in a perhumid ecosystem. This might have favored mineralization of dissolved organic matter (DOM) by microorganisms and increased nutrient release from the organic layer. Environmental change is expected to impact the functioning of this ecosystem belonging to the biodiversity hotspots of the Earth. In 2007, we established a nutrient manipulation experiment (NUMEX) to understand the response of the ecosystem to moderately increased nutrient inputs. Since 2008, we have continuously applied 50 kg ha-1 a-1 of nitrogen (N), 10 kg ha-1 a-1 of phosphorus (P), 50 kg + 10 kg ha-1 a-1 of N and P and 10 kg ha-1 a-1 of calcium (Ca) in a randomized block design at 2000 m a.s.l. in a natural forest on the Amazonia-exposed slopes of the south Ecuadorian Andes. Nitrogen concentrations in throughfall increased following N+P additions, while separate N amendments only increased nitrate concentrations. Total organic carbon (TOC) and dissolved organic nitrogen (DON) concentrations showed high seasonal variations in litter leachate and decreased significantly in the P and N+P treatments, but not in the N treatment. Thus, P availability plays a key role in the mineralization of DOM. TOC/DON ratios were narrower in throughfall than in litter leachate but their temporal course did not respond to nutrient amendments. Our results revealed an initially fast, positive response of the C and N cycling to nutrient additions which declined with time. TOC and DON cycling only change if N and P supply are improved concurrently, while NO3-N leaching increases only if N is separately added. This indicates co-limitation of the microorganisms by N and P

Response of dissolved carbon and nitrogen concentrations to moderate nutrient additions in a tropical montane forest of south Ecuador

Directory of Open Access Journals (Sweden)

Andre eVelescu

2016-05-01

Full Text Available In the past two decades, the tropical montane rain forests in south Ecuador experienced increasing deposition of reactive nitrogen mainly originating from Amazonian forest fires, while Saharan dust inputs episodically increased deposition of base metals. Increasing air temperature and unevenly distributed rainfall have allowed for longer dry spells in a perhumid ecosystem. This might have favored mineralization of dissolved organic matter (DOM by microorganisms and increased nutrient release from the organic layer. Environmental change is expected to impact the functioning of this ecosystem belonging to the biodiversity hotspots of the Earth.In 2007, we established a nutrient manipulation experiment (NUMEX to understand the response of the ecosystem to moderately increased nutrient inputs. Since 2008, we have continuously applied 50 kg ha-1 a-1 of nitrogen (N, 10 kg ha-1 a-1 of phosphorus (P, 50 kg + 10 kg ha-1 a-1 of N and P and 10 kg ha-1 a-1 of calcium (Ca in a randomized block design at 2000 m a.s.l. in a natural forest on the Amazonia-exposed slopes of the south Ecuadorian Andes.Nitrogen concentrations in throughfall increased following N+P additions, while separate N amendments only increased nitrate concentrations. Total organic carbon (TOC and dissolved organic nitrogen (DON concentrations showed high seasonal variations in litter leachate and decreased significantly in the P and N+P treatments, but not in the N treatment. Thus, P availability plays a key role in the mineralization of DOM. TOC/DON ratios were narrower in throughfall than in litter leachate but their temporal course did not respond to nutrient amendments.Our results revealed an initially fast, positive response of the C and N cycling to nutrient additions which declined with time. TOC and DON cycling only change if N and P supply are improved concurrently, while NO3-N leaching increases only if N is separately added. This indicates co-limitation of the microorganisms by N

Increasing nutrient use efficiency through improved feeding and manure manegement in urban and peri-urban livestock units of a West African city: A scenario analysis

NARCIS (Netherlands)

Diogo, V.; Schlecht, E.; Buerkert, A.; Rufino, M.C.; Wijk, van M.T.

2013-01-01

In many African cities urban and peri-urban agriculture (UPA) plays a major role in creating jobs and contributing to food security. However, many small-scale UPA systems are characterised by excessive nutrient inputs to the livestock unit and poor handling of manure. To assess the impact of

Measuring nutrient spiralling in streams

Energy Technology Data Exchange (ETDEWEB)

Newbold, J D; Elwood, J W; O' Neill, R V; Van Winkle, W

1981-01-01

Nutrient cycling in streams involves some downstream transport before the cycle is completed. Thus, the path traveled by a nutrient atom in passing through the cycle can be visualized as a spiral. As an index of the spiralling process, we introduce spiralling length, defined as the average distance associated with one complete cycle of a nutrient atom. This index provides a measure of the utilization of nutrients relative to the available supply from upstream. Using /sup 32/p as a tracer, we estimated a spiralling length of 193 m for phosphorus in a small woodland stream.

A computer simulation of an adaptive noise canceler with a single input

Science.gov (United States)

Albert, Stuart D.

1991-06-01

A description of an adaptive noise canceler using Widrows' LMS algorithm is presented. A computer simulation of canceler performance (adaptive convergence time and frequency transfer function) was written for use as a design tool. The simulations, assumptions, and input parameters are described in detail. The simulation is used in a design example to predict the performance of an adaptive noise canceler in the simultaneous presence of both strong and weak narrow-band signals (a cosited frequency hopping radio scenario). On the basis of the simulation results, it is concluded that the simulation is suitable for use as an adaptive noise canceler design tool; i.e., it can be used to evaluate the effect of design parameter changes on canceler performance.

The role of isotopes in studying nutrient and organic matter dynamics in livestock/cropping systems, with emphasis on carbon and nitrogen

International Nuclear Information System (INIS)

Ledgard, Stewart F.

2002-01-01

Integration of livestock and cropping systems can increase the efficiency of use and recycling of nutrients and other resources. In developing countries, a key goal in mixed animal/cropping systems is maximising production of animals and crops, possibly including grain for human consumption, while minimising the need for inputs of resources such as fertilisers, irrigation water and energy. Low organic N levels in soil in some developing countries, such as in Africa, mean that achievement and maintenance of high yielding crops requires appropriate inputs of organic and/or fertiliser N sources. Improvement in organic matter and N levels in cropping soils are generally achieved via crop rotations or inter-cropping with grain legumes or green manures, or by importing external sources of organic material. Recycling of crop residues is also important for retaining organic matter and nutrients in cropped soils. Increases in the efficiency of these farming systems require a detailed knowledge of the limiting factors or resources for maximising productivity. Isotopes can play a valuable role in identifying, understanding and testing new methodologies associated with soil, water and nutrient resources. Isotopes (particularly 15 N) have been widely used in field studies for determining fertiliser use efficiency, N 2 fixation, and more recently for studying the fate of nutrients from organic materials and crop residues. The major benefit in using isotopes in studies of nutrient use efficiency is that it enables the fate of the nutrient to be traced throughout the soil/plant system even where there are large reserves of the nutrient in soil pools. Most research with isotopes has been restricted to above-ground plant components but some recent studies have targeted plant roots. Foliar 15 N labelling has been used to better quantify root N yields and to determine the uptake of 15 N-labelled root N by subsequent crops. Similarly, 13 CO 2 pulse labelling studies have provided

Effect of fish on water quality and nutrients cycle from an outdoor pond experiment; Sakana no suishitsu, busshitsu junkan ni oyobosu eikyo ni kansuru jikkenteki kenkyu

Energy Technology Data Exchange (ETDEWEB)

Fukushima, T.; Matsushige, K.; Aizaki, M. [National Inst. for Environmental Studies, Tsukuba (Japan); Park, J.; Goma, R. [Tokyo University of Fisheries, Tokyo (Japan); Kong, D. [Korea National Institute of Environmental Research, Seoul (Korea, Republic of)

1995-11-10

The influences of fish (goldfish) on water quality and nutrients cycle (carbon, nitrogen, phosphorus) were investigated during 39 days in the summer of 1993, using six outdoor experimental ponds (36 m{sup 3}) with the same water residence times and nutrient inputs. Blue-been algae dominated the ponds with fish. Compared with ponds without fish, the ponds with high densities of fish had standing stocks of zooplankton and macrozoobenthos nearly one order of magnitude lower, about twice the concentrations of chlorophyll a and twice the rate of primary production. Settling rates of particulate substances in the high density ponds were nearly half those observed in ponds with no fish. The processes of sedimentation and exchange with air played important roles in the nutrient budgets as well as the in- and outflows and the changes in nutrient standing stocks. The high concentrations of chlorophyll a in the fish ponds were attributed in part to the lower zooplankton grazing pressure and in part to the higher nutrient concentrations due to lower settling rates and rapid nutrient recycling between biomass and dissolved components. 28 refs., 8 figs., 6 tabs.

Agronomic Characteristics Related to Grain Yield and Nutrient Use Efficiency for Wheat Production in China.

Directory of Open Access Journals (Sweden)

Limin Chuan

Full Text Available In order to make clear the recent status and trend of wheat (Triticum aestivum L. production in China, datasets from multiple field experiments and published literature were collected to study the agronomic characteristics related to grain yield, fertilizer application and nutrient use efficiency from the year 2000 to 2011. The results showed that the mean grain yield of wheat in 2000-2011 was 5950 kg/ha, while the N, P2O5 and K2O application rates were 172, 102 and 91 kg/ha on average, respectively. The decrease in N and P2O5 and increase in K2O balanced the nutrient supply and was the main reason for yield increase. The partial factor productivity (PFP, kg grain yield produced per unit of N, P2O5 or K2O applied values of N (PFP-N, P (PFP-P and K (PFP-K were in the ranges of 29.5~39.6, 43.4~74.9 and 44.1~76.5 kg/kg, respectively. While PFP-N showed no significant changes from 2000 to 2010, both PFP-P and PFP-K showed an increased trend over this period. The mean agronomic efficiency (AE, kg grain yield increased per unit of N, P2O5 or K2O applied values of N (AEN, P (AEP and K (AEK were 9.4, 10.2 and 6.5 kg/kg, respectively. The AE values demonstrated marked inter-annual fluctuations, with the amplitude of fluctuation for AEN greater than those for AEP and AEK. The mean fertilizer recovery efficiency (RE, the fraction of nutrient uptake in aboveground plant dry matter to the nutrient of fertilizer application values of N, P and K in the aboveground biomass were 33.1%, 24.3% and 28.4%, respectively. It was also revealed that different wheat ecological regions differ greatly in wheat productivity, fertilizer application and nutrient use efficiency. In summary, it was suggested that best nutrient management practices, i.e. fertilizer recommendation applied based on soil testing or yield response, with strategies to match the nutrient input with realistic yield and demand, or provided with the 4R's nutrient management (right time, right rate, right

Workflow Optimization for Tuning Prostheses with High Input Channel

Science.gov (United States)

2017-10-01

of Specific Aim 1 by driving a commercially available two DoF wrist and single DoF hand. The high -level control system will provide analog signals...AWARD NUMBER: W81XWH-16-1-0767 TITLE: Workflow Optimization for Tuning Prostheses with High Input Channel PRINCIPAL INVESTIGATOR: Daniel Merrill...Unlimited The views, opinions and/or findings contained in this report are those of the author(s) and should not be construed as an official Department

Leaf mineral nutrient remobilization during leaf senescence and modulation by nutrient deficiency.

Directory of Open Access Journals (Sweden)

Anne eMaillard

2015-05-01

Full Text Available Higher plants have to cope with fluctuating mineral resource availability. However strategies such as stimulation of root growth, increased transporter activities, and nutrient storage and remobilization have been mostly studied for only a few macronutrients. Leaves of cultivated crops (Zea mays, Brassica napus, Pisum sativum, Triticum aestivum, Hordeum vulgare and tree species (Quercus robur, Populus nigra, Alnus glutinosa grown under field conditions were harvested regularly during their life span and analysed to evaluate the net mobilization of 13 nutrients during leaf senescence. While N was remobilized in all plant species with different efficiencies ranging from 40% (maize to 90% (wheat, other macronutrients (K-P-S-Mg were mobilized in most species. Ca and Mn, usually considered as having low phloem mobility were remobilized from leaves in wheat and barley. Leaf content of Cu-Mo-Ni-B-Fe-Zn decreased in some species, as a result of remobilization. Overall, wheat, barley and oak appeared to be the most efficient at remobilization while poplar and maize were the least efficient. Further experiments were performed with rapeseed plants subjected to individual nutrient deficiencies. Compared to field conditions, remobilization from leaves was similar (N-S-Cu or increased by nutrient deficiency (K-P-Mg while nutrient deficiency had no effect on Mo-Zn-B-Ca-Mn, which seemed to be non-mobile during leaf senescence under field conditions. However, Ca and Mn were largely mobilized from roots (-97 and -86% of their initial root contents, respectively to shoots. Differences in remobilization between species and between nutrients are then discussed in relation to a range of putative mechanisms.

Weak leaf photosynthesis and nutrient content relationships from tropical vegetation

Science.gov (United States)

Domingues, T. F.; Ishida, F. Y.; Feldpaush, T.; Saiz, G.; Grace, J.; Meir, P.; Lloyd, J.

2015-12-01

Evergreen rain forests and savannas are the two major vegetations of tropical land ecosystems, in terms of land area, biomass, biodiversity, biogeochemical cycles and rates of land use change. Mechanistically understanding ecosystem functioning on such ecosystems is still far from complete, but important for generation of future vegetation scenarios in response to global changes. Leaf photosynthetic rates is a key processes usually represented on land surface-atmosphere models, although data from tropical ecosystems is scarce, considering the high biodiversity they contain. As a shortcut, models usually recur to relationships between leaf nutrient concentration and photosynthetic rates. Such strategy is convenient, given the possibility of global datasets on leave nutrients derived from hyperspectral remote sensing data. Given the importance of Nitrogen on enzyme composition, this nutrient is usually used to infer photosynthetic capacity of leaves. Our experience, based on individual measurements on 1809 individual leaves from 428 species of trees and shrubs naturally occurring on tropical forests and savannas from South America, Africa and Australia, indicates that the relationship between leaf nitrogen and its assimilation capacity is weak. Therefore, leaf Nitrogen alone is a poor predictor of photosynthetic rates of tropical vegetation. Phosphorus concentrations from tropical soils are usually low and is often implied that this nutrient limits primary productivity of tropical vegetation. Still, phosphorus (or other nutrients) did not exerted large influence over photosynthetic capacity, although potassium influenced vegetation structure and function. Such results draw attention to the risks of applying universal nitrogen-photosynthesis relationships on biogeochemical models. Moreover, our data suggests that affiliation of plant species within phylogenetic hierarchy is an important aspect in understanding leaf trait variation. The lack of a strong single

Intraglomerular inhibition maintains mitral cell response contrast across input frequencies.

Science.gov (United States)

Shao, Zuoyi; Puche, Adam C; Shipley, Michael T

2013-11-01

Odor signals are transmitted to the olfactory bulb by olfactory nerve (ON) synapses onto mitral/tufted cells (MTCs) and external tufted cells (ETCs); ETCs provide additional feed-forward excitation to MTCs. Both are strongly regulated by intraglomerular inhibition that can last up to 1 s and, when blocked, dramatically increases ON-evoked MC spiking. Intraglomerular inhibition thus limits the magnitude and duration of MC spike responses to sensory input. In vivo, sensory input is repetitive, dictated by sniffing rates from 1 to 8 Hz, potentially summing intraglomerular inhibition. To investigate this, we recorded MTC responses to 1- to 8-Hz ON stimulation in slices. Inhibitory postsynaptic current area (charge) following each ON stimulation was unchanged from 1 to 5 Hz and modestly paired-pulse attenuated at 8 Hz, suggesting there is no summation and only limited decrement at the highest input frequencies. Next, we investigated frequency independence of intraglomerular inhibition on MC spiking. MCs respond to single ON shocks with an initial spike burst followed by reduced spiking decaying to baseline. Upon repetitive ON stimulation peak spiking is identical across input frequencies but the ratio of peak-to-minimum rate before the stimulus (max-min) diminishes from 30:1 at 1 Hz to 15:1 at 8 Hz. When intraglomerular inhibition is selectively blocked, peak spike rate is unchanged but trough spiking increases markedly decreasing max-min firing ratios from 30:1 at 1 Hz to 2:1 at 8 Hz. Together, these results suggest intraglomerular inhibition is relatively frequency independent and can "sharpen" MC responses to input across the range of frequencies. This suggests that glomerular circuits can maintain "contrast" in MC encoding during sniff-sampled inputs.

Effects of Urban Stormwater Infrastructure and Spatial Scale on Nutrient Export and Runoff from Semi-Arid Urban Catchments

Science.gov (United States)

Hale, R. L.; Turnbull, L.; Earl, S.; Grimm, N. B.

2011-12-01

There has been an abundance of literature on the effects of urbanization on downstream ecosystems, particularly due to changes in nutrient inputs as well as hydrology. Less is known, however, about nutrient transport processes and processing in urban watersheds. Engineered drainage systems are likely to play a significant role in controlling the transport of water and nutrients downstream, and variability in these systems within and between cities may lead to differences in the effects of urbanization on downstream ecosystems over time and space. We established a nested stormwater sampling network with 12 watersheds ranging in scale from 5 to 17000 ha in the Indian Bend Wash watershed in Scottsdale, AZ. Small (density residential), but were drained by a variety of stormwater infrastructure including surface runoff, pipes, natural or modified washes, and retention basins. At the outlet of each of these catchments we monitored rainfall and discharge, and sampled stormwater throughout runoff events for dissolved nitrogen (N), phosphorus (P), and organic carbon (oC). Urban stormwater infrastructure is characterized by a range of hydrologic connectivity. Piped watersheds are highly connected and runoff responds linearly to rainfall events, in contrast to watersheds drained with retention basins and washes, where runoff exhibits a nonlinear threshold response to rainfall events. Nutrient loads from piped watersheds scale linearly with total storm rainfall. Because of frequent flushing, nutrient concentrations from these sites are lower than from wash and retention basin drained sites and total nutrient loads exhibit supply limitation, e.g., nutrient loads are poorly predicted by storm rainfall and are strongly controlled by factors that determine the amount of nutrients stored within the watershed, such as antecedent dry days. In contrast, wash and retention basin-drained watersheds exhibit transport limitation. These watersheds flow less frequently than pipe

The subtropical nutrient spiral

Science.gov (United States)

Jenkins, William J.; Doney, Scott C.

2003-12-01

We present an extended series of observations and more comprehensive analysis of a tracer-based measure of new production in the Sargasso Sea near Bermuda using the 3He flux gauge technique. The estimated annually averaged nitrate flux of 0.84 ± 0.26 mol m-2 yr-1 constitutes only that nitrate physically transported to the euphotic zone, not nitrogen from biological sources (e.g., nitrogen fixation or zooplankton migration). We show that the flux estimate is quantitatively consistent with other observations, including decade timescale evolution of the 3H + 3He inventory in the main thermocline and export production estimates. However, we argue that the flux cannot be supplied in the long term by local diapycnal or isopycnal processes. These considerations lead us to propose a three-dimensional pathway whereby nutrients remineralized within the main thermocline are returned to the seasonally accessible layers within the subtropical gyre. We describe this mechanism, which we call "the nutrient spiral," as a sequence of steps where (1) nutrient-rich thermocline waters are entrained into the Gulf Stream, (2) enhanced diapycnal mixing moves nutrients upward onto lighter densities, (3) detrainment and enhanced isopycnal mixing injects these waters into the seasonally accessible layer of the gyre recirculation region, and (4) the nutrients become available to biota via eddy heaving and wintertime convection. The spiral is closed when nutrients are utilized, exported, and then remineralized within the thermocline. We present evidence regarding the characteristics of the spiral and discuss some implications of its operation within the biogeochemical cycle of the subtropical ocean.

Leaf absorption of mineral nutrients in carnivorous plants stimulates root nutrient uptake

Czech Academy of Sciences Publication Activity Database

Adamec, Lubomír

2002-01-01

Roč. 155, - (2002), s. 89-100 ISSN 0028-646X R&D Projects: GA AV ČR IAA6005905 Institutional research plan: CEZ:AV0Z6005908 Keywords : terrestrial carnivorous plant s * utilization of prey * mineral nutrient re-utilization * leaf nutrient supply Subject RIV: EF - Botanics Impact factor: 2.945, year: 2002

CADDIS Volume 2. Sources, Stressors and Responses: Nutrients

Science.gov (United States)

Introduction to the nutrients module, when to list nutrients as a candidate cause, ways to measure nutrients, simple and detailed conceptual diagrams for nutrients, nutrients module references and literature reviews.

A Comparative-Study on Nutrient Cycling in Wet Heathland Ecosystems.2.Litter Decomposition and Nutrient Mineralization

NARCIS (Netherlands)

Berendse, F.; Bobbink, R.; Rouwenhorst, G.

1989-01-01

The concept of the relative nutrient requirement (L n) that was introduced in the first paper of this series is used to analyse the effects of the dominant plant population on nutrient cycling and nutrient mineralization in wet heathland ecosystems. A distinction is made between the effect that the

Leaf nutrient resorption, leaf lifespan and the retention of nutrients in seagrass systems

NARCIS (Netherlands)

Hemminga, M.A.; Marbà, N.; Stapel, J.

1999-01-01

Efficient nutrient resorption from senescing leaves, and extended leaf life spans are important strategies in order to conserve nutrients for plants in general. Despite the fact that seagrasses often grow in oligotrophic waters, these conservation strategies are not strongly developed in seagrasses.

Effects of soil nutrient heterogeneity on intraspecific competition in the invasive, clonal plant Alternanthera philoxeroides.

Science.gov (United States)

Zhou, Jian; Dong, Bi-Cheng; Alpert, Peter; Li, Hong-Li; Zhang, Ming-Xiang; Lei, Guang-Chun; Yu, Fei-Hai

2012-03-01

Fine-scale, spatial heterogeneity in soil nutrient availability can increase the growth of individual plants, the productivity of plant communities and interspecific competition. If this is due to the ability of plants to concentrate their roots where nutrient levels are high, then nutrient heterogeneity should have little effect on intraspecific competition, especially when there are no genotypic differences between individuals in root plasticity. We tested this hypothesis in a widespread, clonal species in which individual plants are known to respond to nutrient heterogeneity. Plants derived from a single clone of Alternanthera philoxeroides were grown in the greenhouse at low or high density (four or 16 plants per 27·5 × 27·5-cm container) with homogeneous or heterogeneous availability of soil nutrients, keeping total nutrient availability per container constant. After 9 weeks, measurements of size, dry mass and morphology were taken. Plants grew more in the heterogeneous than in the homogeneous treatment, showing that heterogeneity promoted performance; they grew less in the high- than in the low-density treatment, showing that plants competed. There was no interactive effect of nutrient heterogeneity and plant density, supporting the hypothesis that heterogeneity does not affect intraspecific competition in the absence of genotypic differences in plasticity. Treatments did not affect morphological characteristics such as specific leaf area or root/shoot ratio. Results indicate that fine-scale, spatial heterogeneity in the availability of soil nutrients does not increase competition when plants are genetically identical, consistent with the suggestion that effects of heterogeneity on competition depend upon differences in plasticity between individuals. Heterogeneity is only likely to increase the spread of monoclonal, invasive populations such as that of A. philoxeroides in China.

Impact of seasonal changes in nutrient loading on distribution and activity of nitrifiers in a tropical estuary

Science.gov (United States)

Vipindas, P. V.; Anas, Abdulaziz; Jayalakshmy, K. V.; Lallu, K. R.; Benny, P. Y.; Shanta, Nair

2018-02-01

Estuaries are ecologically important environments, which function as the reception point of nitrogenous inputs of terrestrial and anthropogenic origin. In the present study, we discuss the influence of nutrient characteristics on the distribution and activity of nitrifiers in the water column of Cochin Estuary (CE), a tropical estuary along the southeast Arabian Sea (SEAS). Nitrifying bacteria (i.e. Ammonia- (AOB) and nitrite- (NOB) -oxidizing bacteria), which were enumerated using fluorescent in situ hybridization (FISH), showed marked seasonality while maintaining the abundance within an order of 107 cells L-1. Denaturing Gradient Gel Electrophoresis (DGGE) analysis of AOB exhibited spatio-temporal adaptability without much variation. Nitrification rate in the CE ranged from 2.25 to 426.17 nmol N L-1 h-1 and it was 10-40 fold higher during the pre-monsoon compared with the monsoon. We attributed this increase to high nutrient availability during pre-monsoon due to low flushing rate of the estuary. The study shows that the distribution and activities of nitrifiers in the CE are modulated by the changes in nutrient concentration imparted by the monsoon-driven seasonal variation in river-water discharge and flushing.

A Three-Phase Dual-Input Matrix Converter for Grid Integration of Two AC Type Energy Resources

DEFF Research Database (Denmark)

Liu, Xiong; Wang, Peng; Chiang Loh, Poh

2013-01-01

This paper proposes a novel dual-input matrix converter (DIMC) to integrate two three-phase ac type energy resources to a power grid. The proposed matrix converter is developed based on the traditional indirect matrix converter under reverse power flow operation mode, but with its six......-to-output voltage boost capability since power flows from the converter’s voltage source side to its current source side. Commanded currents can be extracted from the two input sources to the grid. The proposed control and modulation schemes guarantee sinusoidal input and output waveforms as well as unity input......-switch voltage source converter replaced by a nine-switch configuration. With the additional three switches, the proposed DIMC can provide six in put terminals, which make it possible to integrate two independent ac sources into a single grid-tied power electronics interface. The proposed converter has input...

Total dose induced increase in input offset voltage in JFET input operational amplifiers

International Nuclear Information System (INIS)

Pease, R.L.; Krieg, J.; Gehlhausen, M.; Black, J.

1999-01-01

Four different types of commercial JFET input operational amplifiers were irradiated with ionizing radiation under a variety of test conditions. All experienced significant increases in input offset voltage (Vos). Microprobe measurement of the electrical characteristics of the de-coupled input JFETs demonstrates that the increase in Vos is a result of the mismatch of the degraded JFETs. (authors)

Octopamine connects nutrient cues to lipid metabolism upon nutrient deprivation.

Science.gov (United States)

Tao, Jun; Ma, Yi-Cheng; Yang, Zhong-Shan; Zou, Cheng-Gang; Zhang, Ke-Qin

2016-05-01

Starvation is probably the most common stressful situation in nature. In vertebrates, elevation of the biogenic amine norepinephrine levels is common during starvation. However, the precise role of norepinephrine in nutrient deprivation remains largely unknown. We report that in the free-living nematode Caenorhabditis elegans, up-regulation of the biosynthesis of octopamine, the invertebrate counterpart of norepinephrine, serves as a mechanism to adapt to starvation. During nutrient deprivation, the nuclear receptor DAF-12, known to sense nutritional cues, up-regulates the expression of tbh-1 that encodes tyramine β-hydroxylase, a key enzyme for octopamine biosynthesis, in the RIC neurons. Octopamine induces the expression of the lipase gene lips-6 via its receptor SER-3 in the intestine. LIPS-6, in turn, elicits lipid mobilization. Our findings reveal that octopamine acts as an endocrine regulator linking nutrient cues to lipolysis to maintain energy homeostasis, and suggest that such a mechanism may be evolutionally conserved in diverse organisms.

Optimizing Productivity of Food Crop Genotypes in Low Nutrient Soils

International Nuclear Information System (INIS)

2013-11-01

Global climate change is likely to exacerbate plant abiotic stress in the coming decades by increasing water stress and by accelerating soil fertility degradation. To respond to this set of challenges, there is a need to develop agricultural systems with significantly greater productivity and resilience that at the same time use limited natural resources more efficiently. Low phosphorus (N) and nitrogen (P) availabilities are primary limitations to productivity in low input agriculture, and fertilizers are primary resource inputs in intensive agriculture. A critical feature of future agricultural systems will be new crop varieties with improved conversion of soil resources to yields. These new cultivars would have improved productivity in low input systems and decreased input requirements in high input systems. Many scientists are currently turning their attention to roots, the hidden half of the plant, as central to their efforts to produce crops with better yields without causing environmental damage. Several root traits are known to be associated with P and N acquisition efficiency in low N and P soils. These root traits include root hairs, root length, root branching and root density. The identification of root traits for enhanced P and N acquisition is enabling crop breeders to develop new genotypes with better yields in low fertility soils of Africa, Asia and Latin America. However, in order to use a trait as a selection criterion for crop improvement, either direct phenotypic selection or through marker assisted selection, it is necessary to develop protocols to measure accurately the root traits that enhance N and P acquisition in the glasshouse and in the field, which can provide robust and rapid evaluation of many root systems' architectural traits in targeted production environments using different crops. The objective of the Coordinated Research Project on Optimizing Productivity of Food Crop Genotypes in Low Nutrient Soils was to develop integrated

Optimizing Productivity of Food Crop Genotypes in Low Nutrient Soils

Energy Technology Data Exchange (ETDEWEB)

NONE

2013-11-15

Global climate change is likely to exacerbate plant abiotic stress in the coming decades by increasing water stress and by accelerating soil fertility degradation. To respond to this set of challenges, there is a need to develop agricultural systems with significantly greater productivity and resilience that at the same time use limited natural resources more efficiently. Low phosphorus (N) and nitrogen (P) availabilities are primary limitations to productivity in low input agriculture, and fertilizers are primary resource inputs in intensive agriculture. A critical feature of future agricultural systems will be new crop varieties with improved conversion of soil resources to yields. These new cultivars would have improved productivity in low input systems and decreased input requirements in high input systems. Many scientists are currently turning their attention to roots, the hidden half of the plant, as central to their efforts to produce crops with better yields without causing environmental damage. Several root traits are known to be associated with P and N acquisition efficiency in low N and P soils. These root traits include root hairs, root length, root branching and root density. The identification of root traits for enhanced P and N acquisition is enabling crop breeders to develop new genotypes with better yields in low fertility soils of Africa, Asia and Latin America. However, in order to use a trait as a selection criterion for crop improvement, either direct phenotypic selection or through marker assisted selection, it is necessary to develop protocols to measure accurately the root traits that enhance N and P acquisition in the glasshouse and in the field, which can provide robust and rapid evaluation of many root systems' architectural traits in targeted production environments using different crops. The objective of the Coordinated Research Project on Optimizing Productivity of Food Crop Genotypes in Low Nutrient Soils was to develop integrated

Absorção de nutrientes pelo trigo Absorption of nutrients by wheat plants