Nutrient limitation of soil microbial activity during the earliest stages of ecosystem development.

Science.gov (United States)

Castle, Sarah C; Sullivan, Benjamin W; Knelman, Joseph; Hood, Eran; Nemergut, Diana R; Schmidt, Steven K; Cleveland, Cory C

2017-11-01

A dominant paradigm in ecology is that plants are limited by nitrogen (N) during primary succession. Whether generalizable patterns of nutrient limitation are also applicable to metabolically and phylogenetically diverse soil microbial communities, however, is not well understood. We investigated if measures of N and phosphorus (P) pools inform our understanding of the nutrient(s) most limiting to soil microbial community activities during primary succession. We evaluated soil biogeochemical properties and microbial processes using two complementary methodological approaches-a nutrient addition microcosm experiment and extracellular enzyme assays-to assess microbial nutrient limitation across three actively retreating glacial chronosequences. Microbial respiratory responses in the microcosm experiment provided evidence for N, P and N/P co-limitation at Easton Glacier, Washington, USA, Puca Glacier, Peru, and Mendenhall Glacier, Alaska, USA, respectively, and patterns of nutrient limitation generally reflected site-level differences in soil nutrient availability. The activities of three key extracellular enzymes known to vary with soil N and P availability developed in broadly similar ways among sites, increasing with succession and consistently correlating with changes in soil total N pools. Together, our findings demonstrate that during the earliest stages of soil development, microbial nutrient limitation and activity generally reflect soil nutrient supply, a result that is broadly consistent with biogeochemical theory.

The algal growth-limiting nutrient of lakes located at Mexico’s Mesa Central

Directory of Open Access Journals (Sweden)

Fernando W. Bernal-Brooks

2016-03-01

Full Text Available This paper reports on the algal growth-limiting nutrients of five lakes located on Mexico’s Mesa Central - a topic poorly known in the regional limnology of Mexico. The five case studies involved three contiguous watersheds of Michoacán State and provided a trophic state variation from mesotrophic to hypereutrophic; the case studies included Lakes Zirahuén, Pátzcuaro, Teremendo, Cuitzeo and the Cointzio Reservoir. The fieldwork involved the collection of physical and chemical data (including nutrients from each case study during the dry and rainy seasons of 2010. Additionally, water samples (1 L were obtained and filtered (0.45 µm in the laboratory to keep the nutrient content available for bioassays. The chemical analyses suggested a phosphorus (P limitation in the Cointzio Reservoir, Lake Teremendo and Lake Zirahuén relative to an N:P>16:1. There was a nitrogen (N limitation at three sampling stations of Lake Pátzcuaro, with an N:P<16:1. As result of the bioassays conducted in July 2012, the Cointzio Reservoir and Lake Teremendo appeared to be P-limited and Lake Pátzcuaro appeared to be N-limited at three sampling stations. Lake Zirahuén showed seasonal variation, with an N limitation during the dry season and a P limitation during the wet season. Those cases with similar results from both methods confirmed the limiting nutrient identification. Lake Cuitzeo, Lake Zirahuén (dry season, and the shallowest sampling station in Lake Pátzcuaro produced unclear results because of divergent outcomes. In terms of the algal growth potential, the Cointzio Reservoir remained unaltered from one season to the next. However, for most of the lakes (with the exception of Lake Pátzcuaro sites 2 and 4, the rainy season provided a dilution effect. Effective lake management depends on a clear recognition of such elements that are in control of the aquatic productivity. In the area of Michoacán, both N and P may act as limiting nutrients.

Analogous nutrient limitations in unicellular diazotrophs and Prochlorococcus in the South Pacific Ocean.

Science.gov (United States)

Moisander, Pia H; Zhang, Ruifeng; Boyle, Edward A; Hewson, Ian; Montoya, Joseph P; Zehr, Jonathan P

2012-04-01

Growth limitation of phytoplankton and unicellular nitrogen (N(2)) fixers (diazotrophs) were investigated in the oligotrophic Western South Pacific Ocean. Based on change in abundances of nifH or 23S rRNA gene copies during nutrient-enrichment experiments, the factors limiting net growth of the unicellular diazotrophs UCYN-A (Group A), Crocosphaera watsonii, γ-Proteobacterium 24774A11, and the non-diazotrophic picocyanobacterium Prochlorococcus, varied within the region. At the westernmost stations, numbers were enhanced by organic carbon added as simple sugars, a combination of iron and an organic chelator, or iron added with phosphate. At stations nearest the equator, the nutrient-limiting growth was not apparent. Maximum net growth rates for UCYN-A, C. watsonii and γ-24774A11 were 0.19, 0.61 and 0.52 d(-1), respectively, which are the first known empirical growth rates reported for the uncultivated UCYN-A and the γ-24774A11. The addition of N enhanced total phytoplankton biomass up to 5-fold, and the non-N(2)-fixing Synechococcus was among the groups that responded favorably to N addition. Nitrogen was the major nutrient-limiting phytoplankton biomass in the Western South Pacific Ocean, while availability of organic carbon or iron and organic chelator appear to limit abundances of unicellular diazotrophs. Lack of phytoplankton response to nutrient additions in the Pacific warm pool waters suggests diazotroph growth in this area is controlled by different factors than in the higher latitudes, which may partially explain previously observed variability in community composition in the region.

Substrate and nutrient limitation of ammonia-oxidizing bacteria and archaea in temperate forest soil

Science.gov (United States)

J.S. Norman; J.E. Barrett

2014-01-01

Ammonia-oxidizing microbes control the rate-limiting step of nitrification, a critical ecosystem process, which affects retention and mobility of nitrogen in soil ecosystems. This study investigated substrate (NH4þ) and nutrient (K and P) limitation of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in temperate forest soils at Coweeta Hydrologic...

Controlled copper ion release from phosphate-based glasses improves human umbilical vein endothelial cell survival in a reduced nutrient environment.

Science.gov (United States)

Stähli, Christoph; Muja, Naser; Nazhat, Showan N

2013-02-01

The success of tissue engineering is dependent on rapid scaffold vascularization after engraftment. Copper ions are well known to be angiogenic but exhibit cytotoxicity at elevated doses. The high sensitivity to copper concentration underlines the need of a controlled release mechanism. This study investigated the effect of copper ions released from phosphate-based glasses (PGs) on human umbilical vein endothelial cells (HUVECs) under standard growth conditions (SGC), as well as in a reduced nutrient environment (RNE) with decreased bovine serum and growth factor concentrations to approximate conditions in the core of large volume scaffolds where nutrient diffusion is limited. Initially, HUVECs were exposed to a range of CuCl(2) concentrations in order to identify an optimal response in terms of their metabolism, viability, and apoptotic activity. Under SGC, HUVEC metabolic activity and viability were reduced in a dose-dependent manner in the presence of 0.44-12 ppm Cu(2+). In contrast, HUVEC death induced by the RNE was delayed by an optimal dose of 4 ppm Cu(2+), which was associated with a down-regulation of apoptosis as evidenced by caspase-3/7 activity. Copper ion release from soluble PGs of the formulation 50P(2)O(5)-30CaO-(20-x)Na(2)O-xCuO [mol%] (x=0, 1, 5 and 10) demonstrated a controllable increase with CuO content. The presence of 4 ppm copper ions released from the 10% CuO PG composition reproduced the delay in HUVEC death in the RNE, suggesting the potential of these materials to extend survival of transplanted endothelial cells in large volume scaffolds.

Nutrient availability limits biological production in Arctic sea ice melt ponds

DEFF Research Database (Denmark)

Sørensen, Heidi Louise; Thamdrup, Bo; Jeppesen, Erik

2017-01-01

nutrient limitation in melt ponds. We also document that the addition of nutrients, although at relative high concentrations, can stimulate biological productivity at several trophic levels. Given the projected increase in first-year ice, increased melt pond coverage during the Arctic spring and potential......Every spring and summer melt ponds form at the surface of polar sea ice and become habitats where biological production may take place. Previous studies report a large variability in the productivity, but the causes are unknown. We investigated if nutrients limit the productivity in these first...... additional nutrient supply from, e.g. terrestrial sources imply that biological activity of melt ponds may become increasingly important for the sympagic carbon cycling in the future Arctic....

Nitrogen limitation of growth and nutrient dynamics in a disturbed mangrove forest, Indian River Lagoon, Florida

Science.gov (United States)

Feller, Ilka C.; Whigham, D.F.; McKee, K.L.; Lovelock, C.E.

2003-01-01

The objectives of this study were to determine effects of nutrient enrichment on plant growth, nutrient dynamics, and photosynthesis in a disturbed mangrove forest in an abandoned mosquito impoundment in Florida. Impounding altered the hydrology and soil chemistry of the site. In 1997, we established a factorial experiment along a tree-height gradient with three zones, i.e., fringe, transition, dwarf, and three fertilizer treatment levels, i.e., nitrogen (N), phosphorus (P), control, in Mosquito Impoundment 23 on the eastern side of Indian River. Transects traversed the forest perpendicular to the shoreline, from a Rhizophora mangle-dominated fringe through an Avicennia germinans stand of intermediate height, and into a scrub or dwarf stand of A. germinans in the hinterland. Growth rates increased significantly in response to N fertilization. Our growth data indicated that this site is N-limited along the tree-height gradient. After 2 years of N addition, dwarf trees resembled vigorously growing saplings. Addition of N also affected internal dynamics of N and P and caused increases in rates of photosynthesis. These findings contrast with results for a R. mangle-dominated forest in Belize where the fringe is N-limited, but the dwarf zone is P-limited and the transition zone is co-limited by N and P. This study demonstrated that patterns of nutrient limitation in mangrove ecosystems are complex, that not all processes respond similarly to the same nutrient, and that similar habitats are not limited by the same nutrient when different mangrove forests are compared.

Nutrients in the Canadian environment: reporting on the state of Canada's environment

National Research Council Canada - National Science Library

Ironside, G. R

2001-01-01

This state of the environment (SOE) report is a companion volume to the federal science assessment entitled "Nutrients and their impact on the Canadian enviornment", which was authored by Patricia Chambers, et al...

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

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

Nutrient and Light Limitations on Grass Productivity in a Southern African Savanna

Science.gov (United States)

Ries, L. P.; Shugart, H. H.; Caylor, K. K.; Okin, G. S.; Kgope, B.

2006-12-01

Despite the ubiquity of sub-tropical savannas throughout the earth, limitations of savanna productivity are understudied relative to other terrestrial systems. In particular, there has been little attention on the role of phosphorus (P) in savanna productivity and structure. This study examined the role of increased nitrogen (N) and P in grass productivity in a woodland savanna in Botswana. We added aqueous forms of N and P individually and together to selected grasses. During the following growing season we measured foliar nutrient concentrations, aboveground biomass productivity and photosynthetic response at various levels of incident photosynthetically active radiation to estimate the productivity response. As expected, we observed an increase in foliar P concentrations in P and N+P treatments. However, there was no increase in foliar N for any treatments. We also observed a significant increase in net carbon assimilation and Amax for all treatments relative to the control grasses. Despite a higher rate of leaf level carbon assimilation in the N treatment, the aboveground biomass production was smaller than that of the N+P treatment. These results suggest that the aboveground productivity of these woodland savanna grasses is limited by both N and P. Additionally, under constant CO2 availability, photosynthesis appears to be limited by nutrients for light levels greater than 500 μmol m-2s-1. This research will help broaden our understanding of the biogeochemical processes that govern savanna productivity. Ultimately, these data can be used to model canopy productivity and ecological succession of savannas under scenarios in which bush encroachment and desertification may alter light and nutrients availability.

Long-term seasonal nutrient limiting patterns at Meiliang Bay in a large, shallow and subtropical Lake Taihu, China

Directory of Open Access Journals (Sweden)

Rui Ye

2015-04-01

Full Text Available Lake Taihu has undergone severe eutrophication in the past three decades, and harmful cyanobacteria blooms occur nearly every year in Meiliang Bay at the north end of the lake. To elucidate the potential relationship between seasonal nutrient limitation and phytoplankton proliferation, a 20-year (1991-2012 time series of nutrient limitation in Meiliang Bay was analyzed for deviations between trophic state index (TSI parameters. Results showed that patterns of nutrient limitation in Meiliang Bay were distinctly seasonal, where phytoplankton growth was generally phosphorus (P-limited in winter and spring, but nitrogen (N-limited mainly occurred in summer and fall. This general pattern, however, shifted into N limitation across the four seasons during the mid-1990s because a rapid increase in industrialization led to a significant rise in the input of N and P from inflowing tributaries. The initial patterns were restored by environmental regulation in the end of 1990s, including the Zero Actions plan. Using routine monitoring data, a generalised additive model (GAM with time and deviations between trophic state indexes for nitrogen and phosphorus (TSIN-TSIP as explanatory variables was used to explore which nutrient was responsible for limitation of phytoplankton chlorophyll-a (Chl-a in different seasons. Surprisingly, the model revealed a weak N limitation (TSIN-TSIP = -10 corresponded to peak values of Chl-a in summer-autumn season, which is probably because the phytoplankton community is co-limited by N & P during the period. The shift of nutrition limitation during winter-spring would partially explain high values of Chl-a throughout 1996. This study suggests that seasonal patterns of nutrient limitation must be considered to develop effective management measures to control cyanobacterial blooms.

Nutrients and toxin producing phytoplankton control algal blooms

Indian Academy of Sciences (India)

A phytoplankton-zooplankton prey-predator model has been investigated for temporal, spatial and spatio-temporal dissipative pattern formation in a deterministic and noisy environment, respectively. The overall carrying capacity for the phytoplankton population depends on the nutrient level. The role of nutrient ...

Excess nutrients in hydroponic solutions alter nutrient content of rice, wheat, and potato

Science.gov (United States)

McKeehen, J. D.; Mitchell, C. A.; Wheeler, R. M.; Bugbee, B.; Nielsen, S. S.

1996-01-01

Environment has significant effects on the nutrient content of field-grown crop plants. Little is known, however, about compositional changes caused by controlled environments in which plants receive only artificial radiation and soilless, hydroponic culture. This knowledge is essential for developing a safe, nutritious diet in a Controlled Ecological Life-Support System (CELSS). Three crops that are candidates for inclusion in a CELSS (rice, wheat, and white potato) were grown both in the field and in controlled environments where the hydroponic nutrient solution, photosynthetic photon flux (PPF), and CO2 level were manipulated to achieve rapid growth rates. Plants were harvested at maturity, separated into discrete parts, and dried prior to analysis. Plant materials were analyzed for proximate composition (protein, fat, ash, and carbohydrate), total nitrogen (N), nitrate, minerals, and amino-acid composition. The effect of environment on nutrient content varied by crop and plant part. Total N and nonprotein N (NPN) contents of plant biomass generally increased under controlled-environment conditions compared to field conditions, especially for leafy plant parts and roots. Nitrate levels were increased in hydroponically-grown vegetative tissues, but nitrate was excluded from grains and tubers. Mineral content changes in plant tissue included increased phosphorus and decreased levels of certain micronutrient elements under controlled-environment conditions. These findings suggest that cultivar selection, genetic manipulation, and environmental control could be important to obtain highly nutritious biomass in a CELSS.

Nutrient Content and Nutritional Water Productivity of Selected Grain Legumes in Response to Production Environment.

Science.gov (United States)

Chibarabada, Tendai Polite; Modi, Albert Thembinkosi; Mabhaudhi, Tafadzwanashe

2017-10-26

There is a need to incorporate nutrition into aspects of crop and water productivity to tackle food and nutrition insecurity (FNS). The study determined the nutritional water productivity (NWP) of selected major (groundnut, dry bean) and indigenous (bambara groundnut and cowpea) grain legumes in response to water regimes and environments. Field trials were conducted during 2015/16 and 2016/17 at three sites in KwaZulu-Natal, South Africa (Ukulinga, Fountainhill and Umbumbulu). Yield and evapotranspiration (ET) data were collected. Grain was analysed for protein, fat, Ca, Fe and Zn nutrient content (NC). Yield, ET and NC were then used to compute NWP. Overall, the major legumes performed better than the indigenous grain legumes. Groundnut had the highest NWP fat . Groundnut and dry bean had the highest NWP protein . For NWP Fe, Zn and Ca , dry bean and cowpea were more productive. Yield instability caused fluctuations in NWP. Water treatments were not significant ( p > 0.05). While there is scope to improve NWP under rainfed conditions, a lack of crop improvement currently limits the potential of indigenous grain legumes. This provides an initial insight on the nutrient content and NWP of a limited number of selected grain legumes in response to the production environment. There is a need for follow-up research to include cowpea data. Future studies should provide more experimental data and explore effects of additional factors such as management practices (fertiliser levels and plant density), climate and edaphic factors on nutrient content and NWP of crops.

Including Life Cycle Assessment for decision-making in controlling wastewater nutrient removal systems

DEFF Research Database (Denmark)

Corominas, Lluís; Larsen, Henrik Fred; Flores-Alsina, Xavier

2013-01-01

This paper focuses on the use of Life Cycle Assessment (LCA) to evaluate the performance of seventeen control strategies in wastewater treatment plants (WWTPs). It tackles the importance of using site-specific factors for nutrient enrichment when decision-makers have to select best operating....../or energy savings present an environmental benefit for N&P and P-deficient systems. This is not the case when addressing N-deficient systems for which the use of chemicals (even for improving N removal efficiencies) is not always beneficial for the environment. A sensitivity analysis on using weighting...... of the impact categories is conducted to assess how value choices (policy decisions) may affect the management of WWTPs. For the scenarios with only N-limitation, the LCA-based ranking of the control strategies is sensitive to the choice of weighting factors, whereas this is not the case for N&P or P...

Environmental geochemistry of dissolved and biogenic silicon and its nutrient limitation effects in an inland lake, China.

Science.gov (United States)

Lü, Changwei; He, Jiang; Wang, Bing; Zhou, Bin; Wang, Wei; Fan, Mingde

2015-07-01

Silicon (Si) processing and retention play a key role in nutrients biogeochemistry cycling in aquatic environment. In order to interpret the possibility of Si limitation, multivariate analysis was performed based on stoichiometric nutrients balance, distribution characteristics of dissolved silicon (DSi) and biogenic silica (BSi), adsorption behavior, and response relation of BSi with paleoenvironment in water-sediment system of Lake Daihai. The spatial distributions of DSi and BSi in the water-sediment system indicated that terrigenous inputs (such as the weathering of rock and soil in the drainage basin) was the main sources of Si. Meanwhile, grain sizes of sediments, water hydrogeochemistry, and space competition between diatoms and submergent or emerging plants also played important roles in regulating BSi spatial distributions. The sediments from the lake presented obvious releasing trend of Si at low initial concentrations (≤ 3 mg/L) in adsorption experiments, indicating that the sediments were the source of Si to the overlying water. Furthermore, the good response relation between BSi and paleoenvironment observed in the sediment profiles from Lake Daihai indicated that the main reasons for Si limitation to siliceous plankton were different during different periods. The multi-evidences of distribution characteristics, stoichiometric nutrient balance, adsorption behaviors, and response to paleoenvironment were jointly indicative of Si limitation on the primary production of siliceous plankton in Lake Daihai.

Antioxidant activity and nutrient release from polyphenol-enriched cheese in a simulated gastrointestinal environment.

Science.gov (United States)

Lamothe, Sophie; Langlois, Ariane; Bazinet, Laurent; Couillard, Charles; Britten, Michel

2016-03-01

Green tea polyphenols are recognized for their antioxidant properties and their effects on lipid digestion kinetics. Polyphenols are sensitive to degradation in the intestinal environment. Interactions with dairy proteins could modulate the stability and biological activity of polyphenols during digestion. The objective of this study was to evaluate the release of nutrients (polyphenols, fatty acids and peptides) and the antioxidant activity in polyphenol-enriched cheese containing different levels of calcium in a simulated gastrointestinal environment. The relationship between cheese matrix texture, matrix degradation and nutrient release during digestion was also studied. Green tea extract was added to milk at 0% or 0.1%, and cheeses were produced on a laboratory scale. The level of available calcium was adjusted to low (Ca(low)), regular (Ca(reg)) or high (Ca(high)) during the salting step of the cheese-making process. Cheeses were subjected to simulated digestion. The rate and extent of fatty acid release were 21% lower for Ca(low) cheese than for Ca(reg) and Ca(high) cheeses. The greater adhesiveness of Ca(low) cheese, which resulted in lower rates of matrix degradation and proteolysis, contributed to the reduced rate of lipolysis. The presence of green tea extract in cheese reduced the release of free fatty acids at the end of digestion by 7%. The addition of green tea extract increased cheese hardness but did not influence matrix degradation or proteolysis profiles. The formation of complexes between tea polyphenols and proteins within the cheese matrix resulted in a more than twofold increase in polyphenol recovery in the intestinal phase compared with the control (tea polyphenol extract incubated with polyphenol-free cheese). Antioxidant activity was 14% higher in the digest from polyphenol-enriched cheese than in the control. These results suggest that cheese is an effective matrix for the controlled release of nutrients and for the protection of green

SNF3 as high affinity glucose sensor and its function in supporting the viability of Candida glabrata under glucose-limited environment

Directory of Open Access Journals (Sweden)

Tzu Shan eNg

2015-12-01

Full Text Available Candida glabrata is an emerging human fungal pathogen that has efficacious nutrient sensing and responsiveness ability. It can be seen through its ability to thrive in diverse range of nutrient limited-human anatomical sites. Therefore, nutrient sensing particularly glucose sensing is thought to be crucial in contributing to the development and fitness of the pathogen. This study aimed to elucidate the role of SNF3 (Sucrose Non Fermenting 3 as a glucose sensor and its possible role in contributing to the fitness and survivability of C. glabrata in glucose-limited environment. The SNF3 knockout strain was constructed and subjected to different glucose concentrations to evaluate its growth, biofilm formation, amphotericin B susceptibility, ex vivo survivability and effects on the transcriptional profiling of the sugar receptor repressor (SRR pathway-related genes. The SNF3Δ strain showed a retarded growth in low glucose environments (0.01% and 0.1% in both fermentation and respiration-preferred conditions but grew well in high glucose concentration environments (1% and 2%. It was also found to be more susceptible to amphotericin B in low glucose environment (0.1% and macrophage engulfment but showed no difference in the biofilm formation capability. The deletion of SNF3 also resulted in the down-regulation of about half of hexose transporters genes (4 out of 9. Overall, the deletion of SNF3 causes significant reduction in the ability of C. glabrata to sense limited surrounding glucose and consequently disrupts its competency to transport and perform the uptake of this critical nutrient. This study highlighted the role of SNF3 as a high affinity glucose sensor and its role in aiding the survivability of C. glabrata particularly in glucose limited environment.

Farming of Vegetables in Space-Limited Environments

Science.gov (United States)

He, Jie

2015-10-01

Vegetables that contain most of the essential components of human nutrition are perishable and cannot be stocked. To secure vegetable supply in space limited cities such as Singapore, there are different farming methods to produce vegetables. These include low-cost urban community gardening and innovative rooftop and vertical farms integrated with various technologies such as hydroponics, aquaponics and aeroponics. However, for large-scale vegetable production in space-limited Singapore, we need to develop farming systems that not only increase productivity many-fold per unit of land but also produce all types of vegetable, all year-round for today and the future. This could be resolved through integrated vertical aeroponic farming system. Manipulation of root-zone (RZ) environments such as cooling the RZ, modifying mineral nutrients and introducing elevated RZ CO2 using aeroponics can further boost crop productivity beyond what can be achieved from more efficient use of land area. We could also adopt energy saving light emitting diodes (LEDs) for vertical aeroponic farming system to promote uniform growth and to improve the utilisation of limited space via shortening the growth cycle, thus improving vegetable production in a cost-effective manner.

Expert system for controlling plant growth in a contained environment

Science.gov (United States)

May, George A. (Inventor); Lanoue, Mark Allen (Inventor); Bethel, Matthew (Inventor); Ryan, Robert E. (Inventor)

2011-01-01

In a system for optimizing crop growth, vegetation is cultivated in a contained environment, such as a greenhouse, an underground cavern or other enclosed space. Imaging equipment is positioned within or about the contained environment, to acquire spatially distributed crop growth information, and environmental sensors are provided to acquire data regarding multiple environmental conditions that can affect crop development. Illumination within the contained environment, and the addition of essential nutrients and chemicals are in turn controlled in response to data acquired by the imaging apparatus and environmental sensors, by an "expert system" which is trained to analyze and evaluate crop conditions. The expert system controls the spatial and temporal lighting pattern within the contained area, and the timing and allocation of nutrients and chemicals to achieve optimized crop development. A user can access the "expert system" remotely, to assess activity within the growth chamber, and can override the "expert system".

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

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...

Invasive Acer negundo outperforms native species in non-limiting resource environments due to its higher phenotypic plasticity.

Science.gov (United States)

Porté, Annabel J; Lamarque, Laurent J; Lortie, Christopher J; Michalet, Richard; Delzon, Sylvain

2011-11-24

To identify the determinants of invasiveness, comparisons of traits of invasive and native species are commonly performed. Invasiveness is generally linked to higher values of reproductive, physiological and growth-related traits of the invasives relative to the natives in the introduced range. Phenotypic plasticity of these traits has also been cited to increase the success of invasive species but has been little studied in invasive tree species. In a greenhouse experiment, we compared ecophysiological traits between an invasive species to Europe, Acer negundo, and early- and late-successional co-occurring native species, under different light, nutrient availability and disturbance regimes. We also compared species of the same species groups in situ, in riparian forests. Under non-limiting resources, A. negundo seedlings showed higher growth rates than the native species. However, A. negundo displayed equivalent or lower photosynthetic capacities and nitrogen content per unit leaf area compared to the native species; these findings were observed both on the seedlings in the greenhouse experiment and on adult trees in situ. These physiological traits were mostly conservative along the different light, nutrient and disturbance environments. Overall, under non-limiting light and nutrient conditions, specific leaf area and total leaf area of A. negundo were substantially larger. The invasive species presented a higher plasticity in allocation to foliage and therefore in growth with increasing nutrient and light availability relative to the native species. The higher level of plasticity of the invasive species in foliage allocation in response to light and nutrient availability induced a better growth in non-limiting resource environments. These results give us more elements on the invasiveness of A. negundo and suggest that such behaviour could explain the ability of A. negundo to outperform native tree species, contributes to its spread in European resource

Biocorrosion and biofilm formation in a nutrient limited heating system subjected to alternating microaerophilic conditions.

Science.gov (United States)

Kjellerup, B V; Kjeldsen, K U; Lopes, F; Abildgaard, L; Ingvorsen, K; Frølund, B; Sowers, K R; Nielsen, P H

2009-11-01

Severe biofilm formation and biocorrosion have been observed in heating systems even when the water quality complied with existing standards. The coupling between water chemistry, biofilm formation, species composition, and biocorrosion in a heating system was investigated by adding low concentrations of nutrients and oxygen under continuous and alternating dosing regimes. Molecular analysis of 16S rRNA gene fragments demonstrated that the amendments did not cause changes in the overall bacterial community composition. The combined alternating dosing of nutrients and oxygen caused increased rates of pitting (bio-) corrosion. Detection of bacteria involved in sulfide production and oxidation by retrieval of the functional dsrAB and apsA genes revealed the presence of Gram-positive sulfate- and sulfite-reducers and an unknown sulfur-oxidizer. Therefore, to control biocorrosion, sources of oxygen and nutrients must be limited, since the effect of the alternating operational conditions apparently is more important than the presence of potentially corrosive biofilm bacteria.

Independence of nutrient limitation and carbon dioxide impacts on the Southern Ocean coccolithophore Emiliania huxleyi.

Science.gov (United States)

Müller, Marius N; Trull, Thomas W; Hallegraeff, Gustaaf M

2017-08-01

Future oceanic conditions induced by anthropogenic greenhouse gas emissions include warming, acidification and reduced nutrient supply due to increased stratification. Some parts of the Southern Ocean are expected to show rapid changes, especially for carbonate mineral saturation. Here we compare the physiological response of the model coccolithophore Emiliania huxleyi (strain EHSO 5.14, originating from 50 o S, 149 o E) with pH/CO 2 gradients (mimicking ocean acidification ranging from 1 to 4 × current pCO 2 levels) under nutrient-limited (nitrogen and phosphorus) and -replete conditions. Both nutrient limitations decreased per cell photosynthesis (particulate organic carbon (POC) production) and calcification (particulate inorganic carbon (PIC) production) rates for all pCO 2 levels, with more than 50% reductions under nitrogen limitation. These impacts, however, became indistinguishable from nutrient-replete conditions when normalized to cell volume. Calcification decreased three-fold and linearly with increasing pCO 2 under all nutrient conditions, and was accompanied by a smaller ~30% nonlinear reduction in POC production, manifested mainly above 3 × current pCO 2 . Our results suggest that normalization to cell volume allows the major impacts of nutrient limitation (changed cell sizes and reduced PIC and POC production rates) to be treated independently of the major impacts of increasing pCO 2 and, additionally, stresses the importance of including cell volume measurements to the toolbox of standard physiological analysis of coccolithophores in field and laboratory studies.

Strong hydrological control on nutrient cycling of subtropical rainforests

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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.

Farm management, not soil microbial diversity, controls nutrient loss from smallholder tropical agriculture

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Stephen A Wood

2015-03-01

Full Text Available Tropical smallholder agriculture supports the livelihoods of over 900 million of the world’s poorest people. This form of agriculture is undergoing rapid transformation in nutrient cycling pathways as international development efforts strongly promote greater use of mineral fertilizers to increase crop yields. These changes in nutrient availability may alter the composition of microbial communities with consequences for rates of biogeochemical processes that control nutrient losses to the environment. Ecological theory suggests that altered microbial diversity will strongly influence processes performed by relatively few microbial taxa, such as denitrification and hence nitrogen losses as nitrous oxide, a powerful greenhouse gas. Whether this theory helps predict nutrient losses from agriculture depends on the relative effects of microbial community change and increased nutrient availability on ecosystem processes. We find that mineral and organic nutrient addition to smallholder farms in Kenya alters the taxonomic and functional diversity of soil microbes. However, we find that the direct effects of farm management on both denitrification and carbon mineralization are greater than indirect effects through changes in the taxonomic and functional diversity of microbial communities. Changes in functional diversity are strongly coupled to changes in specific functional genes involved in denitrification, suggesting that it is the expression, rather than abundance, of key functional genes that can serve as an indicator of ecosystem process rates. Our results thus suggest that widely used broad summary statistics of microbial diversity based on DNA may be inappropriate for linking microbial communities to ecosystem processes in certain applied settings. Our results also raise doubts about the relative control of microbial composition compared to direct effects of management on nutrient losses in applied settings such as tropical agriculture.

Nutrient control of eukaryote cell growth: a systems biology study in yeast

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Lilley Kathryn S

2010-05-01

Full Text Available Abstract Background To elucidate the biological processes affected by changes in growth rate and nutrient availability, we have performed a comprehensive analysis of the transcriptome, proteome and metabolome responses of chemostat cultures of the yeast, Saccharomyces cerevisiae, growing at a range of growth rates and in four different nutrient-limiting conditions. Results We find significant changes in expression for many genes in each of the four nutrient-limited conditions tested. We also observe several processes that respond differently to changes in growth rate and are specific to each nutrient-limiting condition. These include carbohydrate storage, mitochondrial function, ribosome synthesis, and phosphate transport. Integrating transcriptome data with proteome measurements allows us to identify previously unrecognized examples of post-transcriptional regulation in response to both nutrient and growth-rate signals. Conclusions Our results emphasize the unique properties of carbon metabolism and the carbon substrate, the limitation of which induces significant changes in gene regulation at the transcriptional and post-transcriptional level, as well as altering how many genes respond to growth rate. By comparison, the responses to growth limitation by other nutrients involve a smaller set of genes that participate in specific pathways. See associated commentary http://www.biomedcentral.com/1741-7007/8/62

Effect of Temperature and Nutrient Concentration on Survival of Foodborne Pathogens in Deciduous Fruit Processing Environments for Effective Hygiene Management.

Science.gov (United States)

Duvenage, Stacey; Korsten, Lise

2016-11-01

Temperature and good sanitation practices are important factors for controlling growth of microorganisms. Fresh produce is stored at various temperatures to ensure quality and to prolong shelf life. When foodborne pathogens survive and grow on fresh produce at storage temperatures, then additional control strategies are needed to inactivate these pathogens. The aim of this study was to determine how temperatures associated with deciduous fruit processing and storage facilities (0.5, 4, and 21°C) affect the growth and/or survival of Escherichia coli O157:H7, Listeria monocytogenes , Salmonella enterica subsp. enterica serovar Typhimurium, and Staphylococcus aureus under different nutrient conditions (nutrient rich and nutrient poor) and on simulated contact surfaces (vinyl coupons). Information on the growth and survival of foodborne pathogens at specific deciduous fruit processing and storage temperatures (0.5°C) is not available. All pathogens except E. coli O157:H7 were able to survive on vinyl coupons at all temperatures. L. monocytogenes proliferated under both nutrient conditions independent of temperature. S. aureus was the pathogen least affected by nutrient conditions. The survival of foodborne pathogens on the vinyl coupons, a model system for studying surfaces in fruit preparation and storage environments, indicates the potential for cross-contamination of deciduous fruit products under poor sanitation conditions. Foodborne pathogens that can proliferate and survive at various temperatures under different nutrient conditions could lead to fruit cross-contamination. Temperature mismanagement, which could allow pathogen proliferation in contaminated fruit packing houses and storage environments, is a concern. Therefore, proper hygiene and sanitation practices, removal of possible contaminants, and proper food safety management systems are needed to ensure food safety.

Infection of Gymnodinium sanguineum by the dinoflagellate Amoebophrya sp.: effect of nutrient environment on parasite generation time, reproduction, and infectivity.

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Yih, W; Coats, D W

2000-01-01

Preliminary attempts to culture Amoebophrya sp., a parasite of Gymnodinium sanguineum from Chesapeake Bay, indicated that success may be influenced by water quality. To explore that possibility, we determined development time, reproductive output, and infectivity of progeny (i.e. dinospores) for Amoebophyra sp. maintained on G. sanguineum grown in four different culture media. The duration of the parasite's intracellular growth phase showed no significant difference among treatments; however, the time required for completion of multiple parasite generations did, with elapsed time to the middle of the third generation being shorter in nutrient-replete media. Parasites of hosts grown in nutrient-replete medium also produced three to four times more dinospores than those infecting hosts under low-nutrient conditions, with mean values of 380 and 130 dinospores/host, respectively. Dinospore production relative to host biovolume also differed, with peak values of 7.4 per 1,000 microm3 host for nutrient-replete medium and 4.8 per 1,000 microm3 host for nutrient-limited medium. Furthermore, dinospores produced by "high-nutrient" parasites had a higher success rate than those formed by "low-nutrient" parasites. Results suggest that Amoebophrya sp. is well adapted to exploit G. sanguineum populations in nutrient-enriched environments.

Cool tadpoles from Arctic environments waste fewer nutrients - high gross growth efficiencies lead to low consumer-mediated nutrient recycling in the North.

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Liess, Antonia; Guo, Junwen; Lind, Martin I; Rowe, Owen

2015-11-01

Endothermic organisms can adapt to short growing seasons, low temperatures and nutrient limitation by developing high growth rates and high gross growth efficiencies (GGEs). Animals with high GGEs are better at assimilating limiting nutrients and thus should recycle (or lose) fewer nutrients. Longer guts in relation to body mass may facilitate higher GGE under resource limitation. Within the context of ecological stoichiometry theory, this study combines ecology with evolution by relating latitudinal life-history adaptations in GGE, mediated by gut length, to its ecosystem consequences, such as consumer-mediated nutrient recycling. In common garden experiments, we raised Rana temporaria tadpoles from two regions (Arctic/Boreal) under two temperature regimes (18/23 °C) crossed with two food quality treatments (high/low-nitrogen content). We measured tadpole GGEs, total nutrient loss (excretion + egestion) rates and gut length during ontogeny. In order to maintain their elemental balance, tadpoles fed low-nitrogen (N) food had lower N excretion rates and higher total phosphorous (P) loss rates than tadpoles fed high-quality food. In accordance with expectations, Arctic tadpoles had higher GGEs and lower N loss rates than their low-latitude conspecifics, especially when fed low-N food, but only in ambient temperature treatments. Arctic tadpoles also had relatively longer guts than Boreal tadpoles during early development. That temperature and food quality interacted with tadpole region of origin in affecting tadpole GGEs, nutrient loss rates and relative gut length, suggests evolved adaptation to temperature and resource differences. With future climate change, mean annual temperatures will increase. Additionally, species and genotypes will migrate north. This will change the functioning of Boreal and Arctic ecosystems by affecting consumer-mediated nutrient recycling and thus affect nutrient dynamics in general. Our study shows that evolved latitudinal adaption can

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

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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

Differential Reliance on Lipid Metabolism as a Salvage Pathway Underlies Functional Differences of T Cell Subsets in Poor Nutrient Environments

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Christopher Ecker

2018-04-01

Full Text Available Summary: T cells compete with malignant cells for limited nutrients within the solid tumor microenvironment. We found that effector memory CD4 T cells respond distinctly from other T cell subsets to limiting glucose and can maintain high levels of interferon-γ (IFN-γ production in a nutrient-poor environment. Unlike naive (TN or central memory T (TCM cells, effector memory T (TEM cells fail to upregulate fatty acid synthesis, oxidative phosphorylation, and reductive glutaminolysis in limiting glucose. Interference of fatty acid synthesis in naive T cells dramatically upregulates IFN-γ, while increasing exogenous lipids in media inhibits production of IFN-γ by all subsets, suggesting that relative ratio of fatty acid metabolism to glycolysis is a direct predictor of T cell effector activity. Together, these data suggest that effector memory T cells are programmed to have limited ability to synthesize and metabolize fatty acids, which allows them to maintain T cell function in nutrient-depleted microenvironments. : Ecker et al. distinguish unique metabolic and functional properties of naive and memory T cell subsets during glucose limitation. During glucose starvation, T cells begin to differentially rely on fatty acid synthesis and glutamine utilization to survive. Unexpectedly, reliance on fatty acid synthesis alters the ability to produce IFN-γ. Keywords: lipid droplets, IFN-γ, oxidative phosphorylation, reductive glutaminolysis, serum-free media, naive T cell, glycolysis, effector memory T cell, fatty acid synthesis

Performance test of nutrient control equipment for hydroponic plants

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Rahman, Nurhaidar; Kuala, S. I.; Tribowo, R. I.; Anggara, C. E. W.; Susanti, N. D.

2017-11-01

Automatic control equipment has been made for the nutrient content in irrigation water for hydroponic plants. Automatic control equipment with CCT53200E conductivity controller to nutrient content in irrigation water for hydroponic plants, can be used to control the amount of TDS of nutrient solution in the range of TDS numbers that can be set according to the range of TDS requirements for the growth of hydroponically cultivated crops. This equipment can minimize the work time of hydroponic crop cultivators. The equipment measurement range is set between 1260 ppm up to 1610 ppm for spinach plants. Caisim plants were included in this experiment along with spinach plants with a spinach plants TDS range. The average of TDS device is 1450 ppm, while manual (conventional) is 1610 ppm. Nutrient solution in TDS controller has pH 5,5 and temperature 29,2 °C, while manual is pH 5,6 and temperature 31,3 °C. Manually treatment to hydroponic plant crop, yields in an average of 39.6 grams/plant, greater than the yield of spinach plants with TDS control equipment, which is in an average of 24.6 grams / plant. The yield of caisim plants by manual treatment is in an average of 32.3 grams/crop, less than caisim crop yields with TDS control equipment, which is in an average of 49.4 grams/plant.

Nutrient Limitation in Surface Waters of the Oligotrophic Eastern Mediterranean Sea: an Enrichment Microcosm Experiment

KAUST Repository

Tsiola, A.

2015-12-01

The growth rates of planktonic microbes in the pelagic zone of the Eastern Mediterranean Sea are nutrient limited, but the type of limitation is still uncertain. During this study, we investigated the occurrence of N and P limitation among different groups of the prokaryotic and eukaryotic (pico-, nano-, and micro-) plankton using a microcosm experiment during stratified water column conditions in the Cretan Sea (Eastern Mediterranean). Microcosms were enriched with N and P (either solely or simultaneously), and the PO4 turnover time, prokaryotic heterotrophic activity, primary production, and the abundance of the different microbial components were measured. Flow cytometric and molecular fingerprint analyses showed that different heterotrophic prokaryotic groups were limited by different nutrients; total heterotrophic prokaryotic growth was limited by P, but only when both N and P were added, changes in community structure and cell size were detected. Phytoplankton were N and P co-limited, with autotrophic pico-eukaryotes being the exception as they increased even when only P was added after a 2-day time lag. The populations of Synechococcus and Prochlorococcus were highly competitive with each other; Prochlorococcus abundance increased during the first 2 days of P addition but kept increasing only when both N and P were added, whereas Synechococcus exhibited higher pigment content and increased in abundance 3 days after simultaneous N and P additions. Dinoflagellates also showed opportunistic behavior at simultaneous N and P additions, in contrast to diatoms and coccolithophores, which diminished in all incubations. High DNA content viruses, selective grazing, and the exhaustion of N sources probably controlled the populations of diatoms and coccolithophores.

External Carbon Source Addition as a Means to Control an Activated Sludge Nutrient Removal Process

DEFF Research Database (Denmark)

Isaacs, Steven Howard; Henze, Mogens; Søeberg, Henrik

1994-01-01

In alternating type activated sludge nutrient removal processes, the denitrification rate can be limited by the availability of readily-degradable carbon substrate. A control strategy is proposed by which an easily metabolizable COD source is added directly to that point in the process at which d...

Implementasi Fuzzy Logic Controller untuk Mengatur Ph Nutrisi pada Sistem Hidroponik Nutrient Film Technique (NFT

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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.

Computer model of hydroponics nutrient solution pH control using ammonium.

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Pitts, M; Stutte, G

1999-01-01

A computer simulation of a hydroponics-based plant growth chamber using ammonium to control pH was constructed to determine the feasibility of such a system. In nitrate-based recirculating hydroponics systems, the pH will increase as plants release hydroxide ions into the nutrient solution to maintain plant charge balance. Ammonium is an attractive alternative to traditional pH controls in an ALSS, but requires careful monitoring and control to avoid overdosing the plants with ammonium. The primary advantage of using NH4+ for pH control is that it exploits the existing plant nutrient uptake charge balance mechanisms to maintain solution pH. The simulation models growth, nitrogen uptake, and pH of a l-m2 stand of wheat. Simulation results indicated that ammonium-based control of nutrient solution pH is feasible using a proportional integral controller. Use of a 1 mmol/L buffer (Ka = 1.6 x 10(-6)) in the nutrient solution is required.

Global dynamics in a stoichiometric food chain model with two limiting nutrients.

Science.gov (United States)

Chen, Ming; Fan, Meng; Kuang, Yang

2017-07-01

Ecological stoichiometry studies the balance of energy and multiple chemical elements in ecological interactions to establish how the nutrient content affect food-web dynamics and nutrient cycling in ecosystems. In this study, we formulate a food chain with two limiting nutrients in the form of a stoichiometric population model. A comprehensive global analysis of the rich dynamics of the targeted model is explored both analytically and numerically. Chaotic dynamic is observed in this simple stoichiometric food chain model and is compared with traditional model without stoichiometry. The detailed comparison reveals that stoichiometry can reduce the parameter space for chaotic dynamics. Our findings also show that decreasing producer production efficiency may have only a small effect on the consumer growth but a more profound impact on the top predator growth. Copyright © 2017 Elsevier Inc. All rights reserved.

THE INFORMATION CONTENT OF THE FARM AND UNIT LEVEL NUTRIENT BALANCES FOR THE MANAGEMENT

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T SOMOGYI

2007-07-01

Full Text Available The farm gate balance is well known from the environmental literature. This method is not suitable in every case to show the nutrient load for the environment of agricultural companies that is the reason why unit level internal nutrient balances are applied to express the level of nutrient pollution on the environment. These also help to determine the source of the pollution. With the survey of the nutrient flows within the farm we determine the keystones of nutrient management to control the nutrient load of the pollution sources. On the basis of the results and the controlled data of the unit level internal balances we make recommendations for the most appropriate environmental policy instrument to reduce the nutrient pollution.

Assessment of macro and micro nutrients around brick kilns agricultural environment

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Abdul Halim Farhad Sikder

2016-03-01

Full Text Available Brick kiln is well known as one of the main sources of air pollution; however, the pollutants produced from it do not remain in the air, they ultimately fall down to the soil and pollute the surroundings, therefore, this study was carried out to assess the status of macro (N, P, K and S and micro nutrients (Fe, Mn and Zn, Cu in the agricultural environment near the brick kilns of Young Brahmaputra and Jamuna Floodplain soils. Composite soil and plant samples were collected from four distances such as 250 m, 500 m, 1000 m, and 1500 m in three different sites. Sulphur (2352–3378 mg kg−1, Zn (86–156 mg kg−1 and Cu (24.7–46.9 mg kg−1 are found in the elevated levels near brick kiln soils that is released due to burning of poor quality coal and fire woods. The alarming news is that plant uptake of S and micro nutrients in the nearest areas of the brick kilns are significantly higher than the areas far from the brick production and their concentration ranges from 23 mg kg−1 to 101 mg kg−1 for Zn, 10–41 mg kg−1 for Cu, 35–1309 mg kg−1 for Fe, 26–126 mg kg−1 for Mn and 2590–mg kg−1 for S. Data indicates both soil and plant received maximum amount of micronutrients and S concentrations within 500–1000 m distances from brick kilns. Iron and Mn concentrations vary within a permissible limit but the plant uptake is high. Nitrogen concentrations is increasing with the distance from the brick kilns in both soils and plants but no definite pattern of P and K accumulation was found. Research suggested avoiding agricultural practice nearby brick kiln soils due to micronutrient contamination in order to preserve adjoined agricultural environment.

Competition for light and nutrients in layered communities of aquatic plants.

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van Gerven, Luuk P A; de Klein, Jeroen J M; Gerla, Daan J; Kooi, Bob W; Kuiper, Jan J; Mooij, Wolf M

2015-07-01

Dominance of free-floating plants poses a threat to biodiversity in many freshwater ecosystems. Here we propose a theoretical framework to understand this dominance, by modeling the competition for light and nutrients in a layered community of floating and submerged plants. The model shows that at high supply of light and nutrients, floating plants always dominate due to their primacy for light, even when submerged plants have lower minimal resource requirements. The model also shows that floating-plant dominance cannot be an alternative stable state in light-limited environments but only in nutrient-limited environments, depending on the plants' resource consumption traits. Compared to unlayered communities, the asymmetry in competition for light-coincident with symmetry in competition for nutrients-leads to fundamentally different results: competition outcomes can no longer be predicted from species traits such as minimal resource requirements ([Formula: see text] rule) and resource consumption. Also, the same two species can, depending on the environment, coexist or be alternative stable states. When applied to two common plant species in temperate regions, both the model and field data suggest that floating-plant dominance is unlikely to be an alternative stable state.

Organic compounds in root exudates of Miscanthus × Giganteus greef et deu and limitation of microorganisms in its rhizosphere by nutrients

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Hana Kaňová

2010-01-01

Full Text Available This study was conducted to determine the composition of sugars and organic acids in root exudates of Miscanthus × Giganteus and to find out if microorganisms of the rhizospheric soil are limited by mi­ne­ral nutrients. The following sugars and organic acids were determined in root exudates of this plant: glucose, saccharose, and acids such as succinic, propionic, citric, tartaric, malic, oxalic, ascorbic, acetic and fumaric. Respiration of soil from rhizosphere of Miscanthus × Giganteus was found to be limited by N, K and Ca. Respiration rate after application of mineral compounds increased in following orther: nitrate > calcium > potassium > ammonium, giving approx. 165, 99, 52 and 31 % increase compared to control. Further research is necessary to determine the role of plant nutrients from the point of their limitations for rhizosphere microorganisms, to broader very rare knowledges in this topic, especially for polluted soils to stimulate efficiency of phytoremediations.

Ethnic disparities among food sources of energy and nutrients of public health concern and nutrients to limit in adults in the United States: NHANES 2003-2006.

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O'Neil, Carol E; Nicklas, Theresa A; Keast, Debra R; Fulgoni, Victor L

2014-01-01

Identification of current food sources of energy and nutrients among US non-Hispanic whites (NHW), non-Hispanic blacks (NHB), and Mexican American (MA) adults is needed to help with public health efforts in implementing culturally sensitive and feasible dietary recommendations. The objective of this study was to determine the food sources of energy and nutrients to limit [saturated fatty acids (SFA), added sugars, and sodium] and nutrients of public health concern (dietary fiber, vitamin D, calcium, and potassium) by NHW, NHB, and MA adults. This was a cross-sectional analysis of a nationally representative sample of NWH (n=4,811), NHB (2,062), and MA (n=1,950) adults 19+ years. The 2003-2006 NHANES 24-h recall (Day 1) dietary intake data were analyzed. An updated USDA Dietary Source Nutrient Database was developed using current food composition databases. Food grouping included ingredients from disaggregated mixtures. Mean energy and nutrient intakes from food sources were sample-weighted. Percentages of total dietary intake contributed from food sources were ranked. Multiple differences in intake among ethnic groups were seen for energy and all nutrients examined. For example, energy intake was higher in MA as compared to NHB; SFA, added sugars, and sodium intakes were higher in NHW than NHB; dietary fiber was highest in MA and lowest in NHB; vitamin D was highest in NHW; calcium was lowest in NHB; and potassium was higher in NHW as compared to NHB. Food sources of these nutrients also varied. Identification of intake of nutrients to limit and of public health concern can help health professionals implement appropriate dietary recommendations and plan interventions that are ethnically appropriate.

Identification and Control of Nutrient Removing Processes in Wastewater Treatment Plants

DEFF Research Database (Denmark)

Nielsen, Marinus K.; Madsen, Henrik; Carstensen, Niels Jacob

1994-01-01

the possibility of using statistical methods for identifying dynamical models for the biological processes. These models can then be used for simulating various control strategies and the parameters of the controllers can be found by off-line optimization. Simulation studies have shown that considerable savings......Today the use of on-line control for wastewater treatment plants is very low. A main reason is the lack of quality of the data, and the fact that more sophisticated control strategies must be based on a model of the dynamics of the biological processes. This paper discusses the historical reasons...... for the limited use of modern control strategies for wastewater treatment plants. Today, however, on-line nutrient sensors are more reliable. In the present context the use of on-line monitored values of ammonia, nitrate and phosphate from a full scale plant are used as the background for discussing...

Hydromorphological control of nutrient cycling in complex river floodplain systems

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Hein, T.; Bondar-Kunze, E.; Felkl, M.; Habersack, H.; Mair, M.; Pinay, G.; Tritthart, M.; Welti, N.

2009-04-01

Riparian zones and floodplains are key components within river ecosystems controlling nutrient cycling by promoting transformation processes and thus, act as biogeochemical hot spots. The intensity of these processes depends on the exchange conditions (the connectivity) with the main channel and the morphological setting of the water bodies. At the landscape scale, three interrelated principles of hydromorphological dynamics can be formulated regarding the cycling and transfer of carbon and nutrients in large rivers ecosystems: a) The mode of carbon and nutrient delivery affects ecosystem functioning; b) Increasing residence time and contact area impact nutrient transformation; c) Floods and droughts are natural events that strongly influence pathways of carbon and nutrient cycling. These three principles of hydromorphological dynamics control the nutrient uptake and retention and are linked over different temporal and spatial scales. All three factors can be strongly affected by natural disturbances or anthropogenic impacts, through a change in either the water regime or the geomorphologic setting of the river valley. Any change in natural water regimes will affect the biogeochemistry of riparian zones and floodplains as well as their ability to cycle and mitigate nutrient fluxes originating from upstream and/or upslope. Especially these areas have been altered by river regulation and land use changes over the last 200 years leading to the deterioration of the functioning of these compartments within the riverine landscape. The resulting deficits have prompted rehabilitation and restoration measures aiming to increase the spatial heterogeneity, the complexity, of these ecosystems. Yet, a more integrated approach is needed considering the present status of nutrient dynamics and the effects of restoration measures at different scales. The present paper analyses the effects of river side-arm restoration on ecosystem functions within the side-arm and highlights

Patterns in foliar nutrient resorption stoichiometry at multiple scales: controlling factors and ecosystem consequences (Invited)

Science.gov (United States)

Reed, S.; Cleveland, C. C.; Davidson, E. A.; Townsend, A. R.

2013-12-01

During leaf senescence, nutrient rich compounds are transported to other parts of the plant and this 'resorption' recycles nutrients for future growth, reducing losses of potentially limiting nutrients. Variations in leaf chemistry resulting from nutrient resorption also directly affect litter quality, in turn, regulating decomposition rates and soil nutrient availability. Here we investigated stoichiometric patterns of nitrogen (N) and phosphorus (P) resorption efficiency at multiple spatial scales. First, we assembled a global database to explore nutrient resorption among and within biomes and to examine potential relationships between resorption stoichiometry and ecosystem nutrient status. Next, we used a forest regeneration chronosequence in Brazil to assess how resorption stoichiometry linked with a suite of other nutrient cycling measures and with ideas of how nutrient limitation may change over secondary forest regrowth. Finally, we measured N:P resorption ratios of six canopy tree species in a Costa Rican tropical forest. We calculated species-specific resorption ratios and compared them with patterns in leaf litter and topsoil nutrient concentrations. At the global scale, N:P resorption ratios increased with latitude and decreased with mean annual temperature (MAT) and precipitation (MAP; P1 in latitudes >23°. Focusing on tropical sites in our global dataset we found that, despite fewer data and a restricted latitudinal range, a significant relationship between latitude and N:P resorption ratios persisted (PAmazon Basin chronosequence of regenerating forests, where previous work reported a transition from apparent N limitation in younger forests to P limitation in mature forests, we found N resorption was highest in the youngest forest, whereas P resorption was greatest in the mature forest. Over the course of succession, N resorption efficiency leveled off but P resorption continued to increase with forest age. In Costa Rica, though we found species

Nutrient limitation reduces land carbon uptake in simulations with a model of combined carbon, nitrogen and phosphorus cycling

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D. S. Goll

2012-09-01

Full Text Available Terrestrial carbon (C cycle models applied for climate projections simulate a strong increase in net primary productivity (NPP due to elevated atmospheric CO₂ concentration during the 21st century. These models usually neglect the limited availability of nitrogen (N and phosphorus (P, nutrients that commonly limit plant growth and soil carbon turnover. To investigate how the projected C sequestration is altered when stoichiometric constraints on C cycling are considered, we incorporated a P cycle into the land surface model JSBACH (Jena Scheme for Biosphere–Atmosphere Coupling in Hamburg, which already includes representations of coupled C and N cycles.

The model reveals a distinct geographic pattern of P and N limitation. Under the SRES (Special Report on Emissions Scenarios A1B scenario, the accumulated land C uptake between 1860 and 2100 is 13% (particularly at high latitudes and 16% (particularly at low latitudes lower in simulations with N and P cycling, respectively, than in simulations without nutrient cycles. The combined effect of both nutrients reduces land C uptake by 25% compared to simulations without N or P cycling. Nutrient limitation in general may be biased by the model simplicity, but the ranking of limitations is robust against the parameterization and the inflexibility of stoichiometry. After 2100, increased temperature and high CO₂ concentration cause a shift from N to P limitation at high latitudes, while nutrient limitation in the tropics declines. The increase in P limitation at high-latitudes is induced by a strong increase in NPP and the low P sorption capacity of soils, while a decline in tropical NPP due to high autotrophic respiration rates alleviates N and P limitations. The quantification of P limitation remains challenging. The poorly constrained processes of soil P sorption and biochemical mineralization are identified as the main uncertainties in the strength of P limitation

Agricultural nutrient loadings to the freshwater environment: the role of climate change and socioeconomic change

Science.gov (United States)

Xie, Hua; Ringler, Claudia

2017-10-01

Human activities, in particular agricultural production, interfere with natural cycles of nutrient elements, nitrogen (N) and phosphorus (P), leading to growing concerns about water quality degradation related to excessive nutrient loadings. Increases in agricultural production in response to population growth and wealth generation further increase risks associated with nutrient pollution. This paper presents results from projections of nutrient exports from global agricultural crop and pasture systems to the water environment generated using a process-based modeling approach. Brazil, China, India and the United States account for more than half of estimated global N and P loadings in the base year. Each country boasts large agriculture centers where high calculated loading values are found. Rapid growth in global agricultural nutrient loadings is projected. Growth of agricultural pollution loading is fastest in the group of low-income developing countries and loading growth rates also vary substantially with climate change scenario. Counter measures need to be taken to address the environmental risks associated with the projected rapid increase of agricultural nutrient loadings.

A Data Base of Nutrient Use, Water Use, CO2 Exchange, and Ethylene Production by Soybeans in a Controlled Environment

Science.gov (United States)

Wheeler, R. M.; Mackowiak, C. L.; Peterson, B. V.; Sager, J. C.; Knott, W. M.; Berry, W. L.; Sharifi, M. R.

1998-01-01

A data set is given describing daily nutrient and water uptake, carbon dioxide (CO2) exchange, ethylene production, and carbon and nutrient partitioning from a 20 sq m stand of soybeans (Glycine max (L.) Merr. cv. McCall] for use in bioregenerative life support systems. Stand CO2 exchange rates were determined from nocturnal increases in CO2 (respiration) and morning drawdowns (net photosynthesis) to a set point of 1000 micromol/ mol each day (i.e., a closed system approach). Atmospheric samples were analyzed throughout growth for ethylene using gas chromatography with photoionization detection (GC/PH)). Water use was monitored by condensate production from the humidity control system, as well as water uptake from the nutrient solution reservoirs each day. Nutrient uptake data were determined from daily additions of stock solution and acid to maintain an EC of 0.12 S/m and pH of 5.8. Dry mass yields of seeds, pods (without seeds), leaves, stems, and roots are provided, as well as elemental and proximate nutritional compositions of the tissues. A methods section is included to qualify any assumptions that might be required for the use of the data in plant growth models, along with a daily event calendar documenting set point adjustments and the occasional equipment or sensor failure.

Hydrothermal Fluid Permeability, Temperature, and Nutrient Fluxes: Three Controls on the Structure and the Dynamics of Subsurface Extremophilic Microbe Communities

Science.gov (United States)

Ryan, M. P.; Yang, J.

2002-05-01

We continue to develop a set of models whose aim is to provide broad constraints on the range of possible community structures for subsurface thermally-tolerant microbes. We combine studies of the three-dimensional internal structure of the dike and sill complexes of active volcanoes, studies of the scale- and direction-dependent 3-D in-situ permeability of intrusive and extrusive rocks from in-situ and laboratory data, numerical modelling of hydrothermal convection in volcanic interiors, data on the optimal metabolic and life-limiting thermal requirements of extremophilic microbes, with the set of nutrients and nutrient pathways required for the survival of given species of thermophiles and hyperthermophiles. With this mix of data bases and analysis tools, we can begin to divine a set of broad theoretical guidelines for constraining the structure and dynamics of extremophilic communities in the subsurface environments of volcanoes. We are searching for the first-order controls on transport. The effects of mineral attachment, detachment, and microbial reproduction may be incorporated in refinements of this basic model. Critical thermal intervals and/or isotherms that correlate with (1) optimal metabolic and (2) life-limiting temperatures for thermophilic microbes are, e.g., in degrees Celcius: Thermus thermophilius [70, 85]; Thermomicrobium roseum [70-75, 85]; Thermus aquaticus [70, 79]; and Sulfolobus acidocaldarius [70-75, 90]. Numerical models of the convective migration of thermophilic (50-80 C), and hyperthermophilic (80-113 C) microbes and their macromolecular amino acid building blocks (113- ~200 C) have been developed that explicitly incorporate the roles of fractures and fluid properties. Fluid transport properties are evaluated through the optimal metabolic and life-limiting temperate ranges and beyond. These models quantify our intuition with respect to controls on community structure and dynamics. Important relationships appear to be: (1) Great

Predicting the profile of nutrients available for absorption: from nutrient requirement to animal response and environmental impact.

Science.gov (United States)

Dijkstra, J; Kebreab, E; Mills, J A N; Pellikaan, W F; López, S; Bannink, A; France, J

2007-02-01

Current feed evaluation systems for dairy cattle aim to match nutrient requirements with nutrient intake at pre-defined production levels. These systems were not developed to address, and are not suitable to predict, the responses to dietary changes in terms of production level and product composition, excretion of nutrients to the environment, and nutrition related disorders. The change from a requirement to a response system to meet the needs of various stakeholders requires prediction of the profile of absorbed nutrients and its subsequent utilisation for various purposes. This contribution examines the challenges to predicting the profile of nutrients available for absorption in dairy cattle and provides guidelines for further improved prediction with regard to animal production responses and environmental pollution.The profile of nutrients available for absorption comprises volatile fatty acids, long-chain fatty acids, amino acids and glucose. Thus the importance of processes in the reticulo-rumen is obvious. Much research into rumen fermentation is aimed at determination of substrate degradation rates. Quantitative knowledge on rates of passage of nutrients out of the rumen is rather limited compared with that on degradation rates, and thus should be an important theme in future research. Current systems largely ignore microbial metabolic variation, and extant mechanistic models of rumen fermentation give only limited attention to explicit representation of microbial metabolic activity. Recent molecular techniques indicate that knowledge on the presence and activity of various microbial species is far from complete. Such techniques may give a wealth of information, but to include such findings in systems predicting the nutrient profile requires close collaboration between molecular scientists and mathematical modellers on interpreting and evaluating quantitative data. Protozoal metabolism is of particular interest here given the paucity of quantitative data

Internal cycling, not external loading, decides the nutrient limitation in eutrophic lake: A dynamic model with temporal Bayesian hierarchical inference.

Science.gov (United States)

Wu, Zhen; Liu, Yong; Liang, Zhongyao; Wu, Sifeng; Guo, Huaicheng

2017-06-01

Lake eutrophication is associated with excessive anthropogenic nutrients (mainly nitrogen (N) and phosphorus (P)) and unobserved internal nutrient cycling. Despite the advances in understanding the role of external loadings, the contribution of internal nutrient cycling is still an open question. A dynamic mass-balance model was developed to simulate and measure the contributions of internal cycling and external loading. It was based on the temporal Bayesian Hierarchical Framework (BHM), where we explored the seasonal patterns in the dynamics of nutrient cycling processes and the limitation of N and P on phytoplankton growth in hyper-eutrophic Lake Dianchi, China. The dynamic patterns of the five state variables (Chla, TP, ammonia, nitrate and organic N) were simulated based on the model. Five parameters (algae growth rate, sediment exchange rate of N and P, nitrification rate and denitrification rate) were estimated based on BHM. The model provided a good fit to observations. Our model results highlighted the role of internal cycling of N and P in Lake Dianchi. The internal cycling processes contributed more than external loading to the N and P changes in the water column. Further insights into the nutrient limitation analysis indicated that the sediment exchange of P determined the P limitation. Allowing for the contribution of denitrification to N removal, N was the more limiting nutrient in most of the time, however, P was the more important nutrient for eutrophication management. For Lake Dianchi, it would not be possible to recover solely by reducing the external watershed nutrient load; the mechanisms of internal cycling should also be considered as an approach to inhibit the release of sediments and to enhance denitrification. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nitrogen regulation of transpiration controls mass-flow acquisition of nutrients.

Science.gov (United States)

Matimati, Ignatious; Verboom, G Anthony; Cramer, Michael D

2014-01-01

Transpiration may enhance mass-flow of nutrients to roots, especially in low-nutrient soils or where the root system is not extensively developed. Previous work suggested that nitrogen (N) may regulate mass-flow of nutrients. Experiments were conducted to determine whether N regulates water fluxes, and whether this regulation has a functional role in controlling the mass-flow of nutrients to roots. Phaseolus vulgaris were grown in troughs designed to create an N availability gradient by restricting roots from intercepting a slow-release N source, which was placed at one of six distances behind a 25 μm mesh from which nutrients could move by diffusion or mass-flow (termed 'mass-flow' treatment). Control plants had the N source supplied directly to their root zone so that N was available through interception, mass-flow, and diffusion (termed 'interception' treatment). 'Mass-flow' plants closest to the N source exhibited 2.9-fold higher transpiration (E), 2.6-fold higher stomatal conductance (gs), 1.2-fold higher intercellular [CO2] (Ci), and 3.4-fold lower water use efficiency than 'interception' plants, despite comparable values of photosynthetic rate (A). E, gs, and Ci first increased and then decreased with increasing distance from the N source to values even lower than those of 'interception' plants. 'Mass-flow' plants accumulated phosphorus and potassium, and had maximum concentrations at 10mm from the N source. Overall, N availability regulated transpiration-driven mass-flow of nutrients from substrate zones that were inaccessible to roots. Thus when water is available, mass-flow may partially substitute for root density in providing access to nutrients without incurring the costs of root extension, although the efficacy of mass-flow also depends on soil nutrient retention and hydraulic properties.

Elemental economy: microbial strategies for optimizing growth in the face of nutrient limitation.

Science.gov (United States)

Merchant, Sabeeha S; Helmann, John D

2012-01-01

Microorganisms play a dominant role in the biogeochemical cycling of nutrients. They are rightly praised for their facility for fixing both carbon and nitrogen into organic matter, and microbial driven processes have tangibly altered the chemical composition of the biosphere and its surrounding atmosphere. Despite their prodigious capacity for molecular transformations, microorganisms are powerless in the face of the immutability of the elements. Limitations for specific elements, either fleeting or persisting over eons, have left an indelible trace on microbial genomes, physiology, and their very atomic composition. We here review the impact of elemental limitation on microbes, with a focus on selected genetic model systems and representative microbes from the ocean ecosystem. Evolutionary adaptations that enhance growth in the face of persistent or recurrent elemental limitations are evident from genome and proteome analyses. These range from the extreme (such as dispensing with a requirement for a hard to obtain element) to the extremely subtle (changes in protein amino acid sequences that slightly, but significantly, reduce cellular carbon, nitrogen, or sulfur demand). One near-universal adaptation is the development of sophisticated acclimation programs by which cells adjust their chemical composition in response to a changing environment. When specific elements become limiting, acclimation typically begins with an increased commitment to acquisition and a concomitant mobilization of stored resources. If elemental limitation persists, the cell implements austerity measures including elemental sparing and elemental recycling. Insights into these fundamental cellular properties have emerged from studies at many different levels, including ecology, biological oceanography, biogeochemistry, molecular genetics, genomics, and microbial physiology. Here, we present a synthesis of these diverse studies and attempt to discern some overarching themes. Copyright © 2012

Experimental evidence for enhanced top-down control of freshwater macrophytes with nutrient enrichment.

Science.gov (United States)

Bakker, Elisabeth S; Nolet, Bart A

2014-11-01

The abundance of primary producers is controlled by bottom-up and top-down forces. Despite the fact that there is consensus that the abundance of freshwater macrophytes is strongly influenced by the availability of resources for plant growth, the importance of top-down control by vertebrate consumers is debated, because field studies yield contrasting results. We hypothesized that these bottom-up and top-down forces may interact, and that consumer impact on macrophyte abundance depends on the nutrient status of the water body. To test this hypothesis, experimental ponds with submerged vegetation containing a mixture of species were subjected to a fertilization treatment and we introduced consumers (mallard ducks, for 8 days) on half of the ponds in a full factorial design. Over the whole 66-day experiment fertilized ponds became dominated by Elodea nuttallii and ponds without extra nutrients by Chara globularis. Nutrient addition significantly increased plant N and P concentrations. There was a strong interactive effect of duck presence and pond nutrient status: macrophyte biomass was reduced (by 50%) after the presence of the ducks on fertilized ponds, but not in the unfertilized ponds. We conclude that nutrient availability interacts with top-down control of submerged vegetation. This may be explained by higher plant palatability at higher nutrient levels, either by a higher plant nutrient concentration or by a shift towards dominance of more palatable plant species, resulting in higher consumer pressure. Including nutrient availability may offer a framework to explain part of the contrasting field observations of consumer control of macrophyte abundance.

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

Reducing Runoff Loss of Applied Nutrients in Oil Palm Cultivation Using Controlled-Release Fertilizers

Directory of Open Access Journals (Sweden)

A. Bah

2014-01-01

Full Text Available Controlled-release fertilizers are expected to minimize nutrient loss from crop fields due to their potential to supply plant-available nutrients in synchrony with crop requirements. The evaluation of the efficiency of these fertilizers in tropical oil palm agroecological conditions is not yet fully explored. In this study, a one-year field trial was conducted to determine the impact of fertilization with water soluble conventional mixture and controlled-release fertilizers on runoff loss of nutrients from an immature oil palm field. Soil and nutrient loss were monitored for one year in 2012/2013 under erosion plots of 16 m2 on 10% slope gradient. Mean sediments concentration in runoff amounted to about 6.41 t ha−1. Conventional mixture fertilizer posed the greatest risk of nutrient loss in runoff following fertilization due to elevated nitrogen (6.97%, potassium (13.37%, and magnesium (14.76% as percentage of applied nutrients. In contrast, this risk decreased with the application of controlled-release fertilizers, representing 0.75–2.44% N, 3.55–5.09% K, and 4.35–5.43% Mg loss. Meanwhile, nutrient loss via eroded sediments was minimal compared with loss through runoff. This research demonstrates that the addition of controlled-release fertilizers reduced the runoff risks of nutrient loss possibly due to their slow-release properties.

Scale and legacy controls on catchment nutrient export regimes

Science.gov (United States)

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

2017-12-01

Nutrient dynamics in river catchments are complex: water and chemical fluxes are highly variable in low-order streams, but this variability declines as fluxes move through higher-order reaches. This poses a major challenge for process understanding as much effort is focussed on long-term monitoring of the main river channel (a high-order reach), and therefore the data available to support process understanding are predominantly derived from sites where much of the transient response of nutrient export is masked by the effect of averaging over both space and time. This may be further exacerbated at all scales by the accumulation of legacy nutrient sources in soils, aquifers and pore waters, where historical activities have led to nutrient accumulation where the catchment system is transport limited. Therefore it is of particular interest to investigate how the variability of nutrient export changes both with catchment scale (from low to high-order catchment streams) and with the presence of legacy sources, such that the context of infrequent monitoring on high-order streams can be better understood. This is not only a question of characterising nutrient export regimes per se, but also developing a more thorough understanding of how the concepts of scale and legacy may modify the statistical characteristics of observed responses across scales in both space and time. In this paper, we use synthetic data series and develop a model approach to consider how space and timescales combine with impacts of legacy sources to influence observed variability in catchment export. We find that: increasing space and timescales tend to reduce the observed variance in nutrient exports, due to an increase in travel times and greater mixing, and therefore averaging, of sources; increasing the influence of legacy sources inflates the variance, with the level of inflation dictated by the residence time of the respective sources.

Principles for limiting releases of radioactive effluents into the environment

International Nuclear Information System (INIS)

1986-01-01

This publication is concerned with the subject of limiting releases of radioactive effluents during normal, controlled operation of nuclear installations. It does not deal with releases from accidents where it is only possible to limit exposures by intervention. In 1978 the IAEA published guidance on the concepts and principles for use by the competent authorities in setting limits for planned releases of radioactive material into the environment (Safety Series No. 45). This publication is a complete revision of Safety Series No. 45 and its Annex

Nutrient regulation by continuous feeding removes limitations on cell yield in the large-scale expansion of Mammalian cell spheroids.

Directory of Open Access Journals (Sweden)

Bradley P Weegman

Full Text Available Cellular therapies are emerging as a standard approach for the treatment of several diseases. However, realizing the promise of cellular therapies across the full range of treatable disorders will require large-scale, controlled, reproducible culture methods. Bioreactor systems offer the scale-up and monitoring needed, but standard stirred bioreactor cultures do not allow for the real-time regulation of key nutrients in the medium. In this study, β-TC6 insulinoma cells were aggregated and cultured for 3 weeks as a model of manufacturing a mammalian cell product. Cell expansion rates and medium nutrient levels were compared in static, stirred suspension bioreactors (SSB, and continuously fed (CF SSB. While SSB cultures facilitated increased culture volumes, no increase in cell yields were observed, partly due to limitations in key nutrients, which were consumed by the cultures between feedings, such as glucose. Even when glucose levels were increased to prevent depletion between feedings, dramatic fluctuations in glucose levels were observed. Continuous feeding eliminated fluctuations and improved cell expansion when compared with both static and SSB culture methods. Further improvements in growth rates were observed after adjusting the feed rate based on calculated nutrient depletion, which maintained physiological glucose levels for the duration of the expansion. Adjusting the feed rate in a continuous medium replacement system can maintain the consistent nutrient levels required for the large-scale application of many cell products. Continuously fed bioreactor systems combined with nutrient regulation can be used to improve the yield and reproducibility of mammalian cells for biological products and cellular therapies and will facilitate the translation of cell culture from the research lab to clinical applications.

Nutrient Regulation by Continuous Feeding Removes Limitations on Cell Yield in the Large-Scale Expansion of Mammalian Cell Spheroids

Science.gov (United States)

Weegman, Bradley P.; Nash, Peter; Carlson, Alexandra L.; Voltzke, Kristin J.; Geng, Zhaohui; Jahani, Marjan; Becker, Benjamin B.; Papas, Klearchos K.; Firpo, Meri T.

2013-01-01

Cellular therapies are emerging as a standard approach for the treatment of several diseases. However, realizing the promise of cellular therapies across the full range of treatable disorders will require large-scale, controlled, reproducible culture methods. Bioreactor systems offer the scale-up and monitoring needed, but standard stirred bioreactor cultures do not allow for the real-time regulation of key nutrients in the medium. In this study, β-TC6 insulinoma cells were aggregated and cultured for 3 weeks as a model of manufacturing a mammalian cell product. Cell expansion rates and medium nutrient levels were compared in static, stirred suspension bioreactors (SSB), and continuously fed (CF) SSB. While SSB cultures facilitated increased culture volumes, no increase in cell yields were observed, partly due to limitations in key nutrients, which were consumed by the cultures between feedings, such as glucose. Even when glucose levels were increased to prevent depletion between feedings, dramatic fluctuations in glucose levels were observed. Continuous feeding eliminated fluctuations and improved cell expansion when compared with both static and SSB culture methods. Further improvements in growth rates were observed after adjusting the feed rate based on calculated nutrient depletion, which maintained physiological glucose levels for the duration of the expansion. Adjusting the feed rate in a continuous medium replacement system can maintain the consistent nutrient levels required for the large-scale application of many cell products. Continuously fed bioreactor systems combined with nutrient regulation can be used to improve the yield and reproducibility of mammalian cells for biological products and cellular therapies and will facilitate the translation of cell culture from the research lab to clinical applications. PMID:24204645

Monitoring of nutrient limitation in growing E. coli: a mathematical model of a ppGpp-based biosensor.

Science.gov (United States)

Pokhilko, Alexandra

2017-11-21

E. coli can be used as bacterial cell factories for production of biofuels and other useful compounds. The efficient production of the desired products requires careful monitoring of growth conditions and the optimization of metabolic fluxes. To avoid nutrient depletion and maximize product yields we suggest using a natural mechanism for sensing nutrient limitation, related to biosynthesis of an intracellular messenger - guanosine tetraphosphate (ppGpp). We propose a design for a biosensor, which monitors changes in the intracellular concentration of ppGpp by coupling it to a fluorescent output. We used mathematical modelling to analyse the intracellular dynamics of ppGpp, its fluorescent reporter, and cell growth in normal and fatty acid-producing E. coli lines. The model integrates existing mechanisms of ppGpp regulation and predicts the biosensor response to changes in nutrient state. In particular, the model predicts that excessive stimulation of fatty acid production depletes fatty acid intermediates, downregulates growth and increases the levels of ppGpp-related fluorescence. Our analysis demonstrates that the ppGpp sensor can be used for early detection of nutrient limitation during cell growth and for testing productivity of engineered lines.

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

Nutrient amendment does not increase mineralisation of sequestered carbon during incubation of a nitrogen limited mangrove soil

KAUST Repository

Keuskamp, Joost A.

2013-02-01

Mangrove forests are sites of intense carbon and nutrient cycling, which result in soil carbon sequestration on a global scale. Currently, mangrove forests receive increasing quantities of exogenous nutrients due to coastal development. The present paper quantifies the effects of nutrient loading on microbial growth rates and the mineralisation of soil organic carbon (SOC) in two mangrove soils contrasting in carbon content. An increase in SOC mineralisation rates would lead to the loss of historically sequestered carbon and an enhanced CO2 release from these mangrove soils.In an incubation experiment we enriched soils from Avicennia and Rhizophora mangrove forests bordering the Red Sea with different combinations of nitrogen, phosphorus and glucose to mimic the effects of wastewater influx. We measured microbial growth rates as well as carbon mineralisation rates in the natural situation and after enrichment. The results show that microbial growth is energy limited in both soils, with nitrogen as a secondary limitation. Nitrogen amendment increased the rate at which labile organic carbon was decomposed, while it decreased SOC mineralisation rates. Such an inhibitory effect on SOC mineralisation was not found for phosphorus enrichment.Our data confirm the negative effect of nitrogen enrichment on the mineralisation of recalcitrant carbon compounds found in other systems. Based on our results it is not to be expected that nutrient enrichment by itself will cause degradation of historically sequestered soil organic carbon in nitrogen limited mangrove forests. © 2012 Elsevier Ltd.

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

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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

Nutrient demand and fungal access to resources control the carbon allocation to the symbiotic partners in tripartite interactions of Medicago truncatula.

Science.gov (United States)

Kafle, Arjun; Garcia, Kevin; Wang, Xiurong; Pfeffer, Philip E; Strahan, Gary D; Bücking, Heike

2018-06-02

Legumes form tripartite interactions with arbuscular mycorrhizal (AM) fungi and rhizobia, and both root symbionts exchange nutrients against carbon from their host. The carbon costs of these interactions are substantial, but our current understanding of how the host controls its carbon allocation to individual root symbionts is limited. We examined nutrient uptake and carbon allocation in tripartite interactions of Medicago truncatula under different nutrient supply conditions, and when the fungal partner had access to nitrogen, and followed the gene expression of several plant transporters of the SUT and SWEET family. Tripartite interactions led to synergistic growth responses and stimulated the phosphate and nitrogen uptake of the plant. Plant nutrient demand but also fungal access to nutrients played an important role for the carbon transport to different root symbionts, and the plant allocated more carbon to rhizobia under nitrogen demand, but more carbon to the fungal partner when nitrogen was available. These changes in carbon allocation were consistent with changes in the SUT and SWEET expression. Our study provides important insights into how the host plant controls its carbon allocation under different nutrient supply conditions and changes its carbon allocation to different root symbionts to maximize its symbiotic benefits. This article is protected by copyright. All rights reserved.

Nutrient limitation on ecosystem productivity and processes of mature and old-growth subtropical forests in China.

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Enqing Hou

Full Text Available Nitrogen (N is considered the dominant limiting nutrient in temperate regions, while phosphorus (P limitation frequently occurs in tropical regions, but in subtropical regions nutrient limitation is poorly understood. In this study, we investigated N and P contents and N:P ratios of foliage, forest floors, fine roots and mineral soils, and their relationships with community biomass, litterfall C, N and P productions, forest floor turnover rate, and microbial processes in eight mature and old-growth subtropical forests (stand age >80 yr at Dinghushan Biosphere Reserve, China. Average N:P ratios (mass based in foliage, litter (L layer and mixture of fermentation and humus (F/H layer, and fine roots were 28.3, 42.3, 32.0 and 32.7, respectively. These values are higher than the critical N:P ratios for P limitation proposed (16-20 for foliage, ca. 25 for forest floors. The markedly high N:P ratios were mainly attributed to the high N concentrations of these plant materials. Community biomass, litterfall C, N and P productions, forest floor turnover rate and microbial properties were more strongly related to measures of P than N and frequently negatively related to the N:P ratios, suggesting a significant role of P availability in determining ecosystem production and productivity and nutrient cycling at all the study sites except for one prescribed disturbed site where N availability may also be important. We propose that N enrichment is probably a significant driver of the potential P limitation in the study area. Low P parent material may also contribute to the potential P limitation. In general, our results provided strong evidence supporting a significant role for P availability, rather than N availability, in determining ecosystem primary productivity and ecosystem processes in subtropical forests of China.

Assessment of Nutrient Limitation in Flood plain Forests with Two Different Techniques

International Nuclear Information System (INIS)

Neatrour, M.A.; Jones, R.H.; Golladay, S.W.

2008-01-01

We assessed nitrogen and phosphorus limitation in a flood plain forest in southern Georgia in USA using two commonly used methods: nitrogen to phosphorus (N:P) ratios in litterfall and fertilized ingrowth cores. We measured nitrogen (N) and phosphorus (P) concentrations in litterfall to determine N:P mass ratios. We also installed ingrowth cores within each site containing native soil amended with nitrogen (N), phosphorus (P), or nitrogen and phosphorus (N + P) fertilizers or without added fertilizer (C). Litter N:P ratios ranged from 16 to 22, suggesting P limitation. However, fertilized ingrowth cores indicated N limitation because fine-root length density was greater in cores fertilized with N or N + P than in those fertilized with P or without added fertilizer. We feel that these two methods of assessing nutrient limitation should be corroborated with fertilization trials prior to use on a wider basis.

Nutrient-enhanced growth of Cladophora prolifera in harrington sound, bermuda: Eutrophication of a confined, phosphorus-limited marine ecosystem

Science.gov (United States)

Lapointe, Brian E.; O'Connell, Julie

1989-04-01

The green alga Cladophora prolifera (Chlorophyta, Cladophorales) has formed widespread blooms in Bermuda's inshore waters during the past 20 years, but, to date, no conclusive evidence links these blooms to nutrient enrichment. This study assessed the nutrient-dependance of productivity of Cladophora collected from Harrington Sound, a confined P-limited marine system where Cladophora first became abundant. Both N- and P-enrichment decreased the doubling time of Cladophora, which ranged from 14 days (with N and P enrichment) to 100 days (without enrichment). Nutrient enrichment also enhanced the light-saturated photosynthetic capacity (i.e. P max) of Cladophora, which ranged from 0·50 mg C g dry wt -1 h -1 (without enrichment) to 1·0 mg C g dry wt -1 h -1 (with enrichment). Tissue C:N, C:P and N:P ratios of unenriched Cladophora were elevated—25, 942, and 49, respectively—levels that suggest limitation by both N and P but primary limitation by P. Pore-waters under Cladophora mats had reduced salinities, elevated concentrations of NH 4, and high N:P ratios (N:P of 85), suggesting that N-rich groundwater seepage enriches Cladophora mats. The alkaline phosphatase capacity of Cladophora was high compared to other macroalgae in Harrington Sound, and its capacity was enhanced by N-enrichment and suppressed by P-enrichment. Because the productivity of Cladophora is nutrient-limited in shallow waters of Harrington Sound, enhanced growth and increased biomass of Cladophora result from cumulative seepage of N-rich groundwaters coupled with efficient utilization and recycling of dissolved organo-phosphorus compounds.

The role of diatom nanostructures in biasing diffusion to improve uptake in a patchy nutrient environment.

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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.

Thermosyphon Flooding Limits in Reduced Gravity Environments

Science.gov (United States)

Gibson, Marc A.; Jaworske, Donald A.; Sanzi, James L.; Ljubanovic, Damir

2012-01-01

Fission Power Systems have long been recognized as potential multi-kilowatt power solutions for lunar, Martian, and extended planetary surface missions. Current heat rejection technology associated with fission surface power systems has focused on titanium water thermosyphons embedded in carbon composite radiator panels. The thermosyphons, or wickless heat pipes, are used as a redundant and efficient way to spread the waste heat from the power conversion unit(s) over the radiator surface area where it can be rejected to space. It is well known that thermosyphon performance is reliant on gravitational forces to keep the evaporator wetted with the working fluid. One of the performance limits that can be encountered, if not understood, is the phenomenon of condenser flooding, otherwise known as evaporator dry out. This occurs when the gravity forces acting on the condensed fluid cannot overcome the shear forces created by the vapor escaping the evaporator throat. When this occurs, the heat transfer process is stalled and may not re-stabilize to effective levels without corrective control actions. The flooding limit in earth's gravity environment is well understood as experimentation is readily accessible, but when the environment and gravity change relative to other planetary bodies, experimentation becomes difficult. An innovative experiment was designed and flown on a parabolic flight campaign to achieve the Reduced Gravity Environments (RGE) needed to obtain empirical data for analysis. The test data is compared to current correlation models for validation and accuracy.

Acclimation of Emiliania huxleyi (1516) to nutrient limitation involves precise modification of the proteome to scavenge alternative sources of N and P.

Science.gov (United States)

McKew, Boyd A; Metodieva, Gergana; Raines, Christine A; Metodiev, Metodi V; Geider, Richard J

2015-10-01

Limitation of marine primary production by the availability of nitrogen or phosphorus is common. Emiliania huxleyi, a ubiquitous phytoplankter that plays key roles in primary production, calcium carbonate precipitation and production of dimethyl sulfide, often blooms in mid-latitude at the beginning of summer when inorganic nutrient concentrations are low. To understand physiological mechanisms that allow such blooms, we examined how the proteome of E. huxleyi (strain 1516) responds to N and P limitation. We observed modest changes in much of the proteome despite large physiological changes (e.g. cellular biomass, C, N and P) associated with nutrient limitation of growth rate. Acclimation to nutrient limitation did however involve significant increases in the abundance of transporters for ammonium and nitrate under N limitation and for phosphate under P limitation. More notable were large increases in proteins involved in the acquisition of organic forms of N and P, including urea and amino acid/polyamine transporters and numerous C-N hydrolases under N limitation and a large upregulation of alkaline phosphatase under P limitation. This highly targeted reorganization of the proteome towards scavenging organic forms of macronutrients gives unique insight into the molecular mechanisms that underpin how E. huxleyi has found its niche to bloom in surface waters depleted of inorganic nutrients. © 2015 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

Interactions between soil texture, water, and nutrients control patterns of biocrusts abundance and structure

Science.gov (United States)

Young, Kristina; Bowker, Matthew; Reed, Sasha; Howell, Armin

2017-04-01

Heterogeneity in the abiotic environment structures biotic communities by controlling niche space and parameters. This has been widely observed and demonstrated in vascular plant and other aboveground communities. While soil organisms are presumably also strongly influenced by the physical and chemical dimensions of the edaphic environment, there are fewer studies linking the development, structure, productivity or function of surface soil communities to specific edaphic gradients. Here, we use biological soil crusts (biocrusts) as a model system to determine mechanisms regulating community structure of soil organisms. We chose soil texture to serve as an edaphic gradient because of soil texture's influence over biocrust distribution on a landscape level. We experimentally manipulated texture in constructed soil, and simultaneously manipulated two main outcomes of texture, water and nutrient availability, to determine the mechanism underlying texture's influence on biocrust abundance and structure. We grew biocrust communities from a field-sourced inoculum on four different soil textures, sieved from the same parent soil material, manipulating watering levels and nutrient additions across soil textures in a full-factorial design over a 5-month period of time. We measured abundance and structure of biocrusts over time, and measured two metrics of function, N2 fixation rates and soil stabilization, at the conclusion of the experiment. Our results showed finer soil textures resulted in faster biocrust community development and dominance by mosses, whereas coarser textures grew more slowly and had biocrust communities dominated by cyanobacteria and lichen. Additionally, coarser textured soils contained cyanobacterial filaments significantly deeper into the soil profile than fine textured soils. N2-fixation values increased with increasing moss cover and decreased with increasing cyanobacterial cover, however, the rate of change depended on soil texture and water amount

New approaches to deriving limits of the release of radioactive material into the environment

International Nuclear Information System (INIS)

Lindell, B.

1977-01-01

During the last few years, new principles have been developed for the limitation of the release of radioactive material into the environment. It is no longer considered appropriate to base the limitation on limits for the concentrations of the various radionuclides in air and water effluents. Such limits would not prevent large amounts of radioactive material from reaching the environment should effluent rates be high. A common practice has been to identify critical radionuclides and critical pathways and to base the limitation on authorized dose limits for local ''critical groups''. If this were the only limitation, however, larger releases could be permitted after installing either higher stacks or equipment to retain the more short-lived radionuclides for decay before release. Continued release at such limits would then lead to considerably higher exposure at a distance than if no such installation had been made. Accordingly there would be no immediate control of overlapping exposures from several sources, nor would the system guarantee control of the future situation. The new principles described in this paper take the future into account by limiting the annual dose commitments rather than the annual doses. They also offer means of controlling the global situation by limiting not only doses in critical groups but also global collective doses. Their objective is not only to ensure that individual dose limits will always be respected but also to meet the requirement that ''all doses be kept as low as reasonably achievable''. The new approach is based on the most recent recommendations by the ICRP and has been described in a report by an IAEA panel (Procedures for establishing limits for the release of radioactive material into the environment). It has been applied in the development of new Swedish release regulations, which illustrate some of the problems which arise in the practical application

New approaches to deriving limits of the release of radioactive material into the environment

International Nuclear Information System (INIS)

Lindell, B.

1977-01-01

During the last few years, new principles have been developed for the limitation of the release of radioactive material into the environment. It is no longer considered appropriate to base the limitation on limits for the concentrations of the various radionuclides in air and water effluents. Such limits would not prevent large amounts of radioactive material from reaching the environment should effluent rates be high. A common practice has been to identify critical radionuclides and critical pathways and to base the limitation on authorized dose limits for local ''critical groups''. If this were the only limitation, however, larger releases could be permitted after installing either higher stacks or equipment to retain the more shortlived radionuclides for decay before release. Continued release at such limits would then lead to considerably higher exposure at a distance than if no such installation had been made. Accordingly there would be no immediate control of overlapping exposures from several sources, nor would the system guarantee control of the future situation. The new principles described in this paper take the future into account by limiting the annual dose commitments rather than the annual doses. They also offer means of controlling the global situation by limiting not only doses in critical groups but also global collective doses. Their objective is not only to ensure that individual dose limits will always be respected but also to meet the requirement that ''all doses be kept as low as reasonably achievable''. The new approach is based on the most recent recommendations by the ICRP and has been described in a report by an IAEA panel (Procedures for Establishing Limits for the Release of Radioactive Material into the Environment). It has been applied in the development of new Swedish release regulations, which illustrate some of the problems which arise in the practical application. (author)

Proximate and ultimate controls on carbon and nutrient dynamics of small agricultural catchments

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Thomas, Zahra; Abbott, Benjamin W.; Troccaz, Olivier; Baudry, Jacques; Pinay, Gilles

2016-03-01

Direct and indirect effects from human activity have dramatically increased nutrient loading to aquatic inland and estuarine ecosystems. Despite an abundance of studies investigating the impact of agricultural activity on water quality, our understanding of what determines the capacity of a watershed to remove or retain nutrients remains limited. The goal of this study was to identify proximate and ultimate controls on dissolved organic carbon and nutrient dynamics in small agricultural catchments by investigating the relationship between catchment characteristics, stream discharge, and water chemistry. We analyzed a 5-year, high-frequency water chemistry data set from three catchments in western France ranging from 2.3 to 10.8 km2. The relationship between hydrology and solute concentrations differed between the three catchments and was associated with hedgerow density, agricultural activity, and geology. The catchment with thicker soil and higher surface roughness had relatively invariant carbon and nutrient chemistry across hydrologic conditions, indicating high resilience to human disturbance. Conversely, the catchments with smoother, thinner soils responded to both intra- and interannual hydrologic variation with high concentrations of phosphate (PO43-) and ammonium (NH4+) in streams during low flow conditions and strong increases in dissolved organic carbon (DOC), sediment, and particulate organic matter during high flows. Despite contrasting agricultural activity between catchments, the physical context (geology, topography, and land-use configuration) appeared to be the most important determinant of catchment solute dynamics based on principle components analysis. The influence of geology and accompanying topographic and geomorphological factors on water quality was both direct and indirect because the distribution of agricultural activity in these catchments is largely a consequence of the geologic and topographic context. This link between inherent

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.

Nutrient patterns and risk of cataract: a case-control study

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Fatemeh Sedaghat

2017-04-01

Full Text Available AIM: To assess the relation between nutrient patterns and cataract risk. METHODS: This is a hospital-based case-control study with 97 cataract patients and 198 matched controls. Dietary consumption was collected through a valid food frequency questionnaire (FFQ. Nutrient patterns were detected by applying factor analysis. Unconditional logistic regression models were used to estimate odds ratio (ORs and 95%CIs. RESULTS: We extracted 5 main nutrient patterns. Factor 1 included niacin, thiamin, carbohydrates, protein, zinc, vitamin B6 and sodium (sodium pattern. Factor 2 was characterized by oleic acid, monounsaturated fats, polyunsaturated fats, linoleic acid, trans fatty acid, linolenic acid, vitamin E and saturated fats (fatty acid pattern. The third factor represented high intake of vitamin B12, vitamin D, cholesterol and calcium (mixed pattern. The 4th pattern was high in intake of beta and alpha carotene, vitamin A and vitamin C (antioxidant pattern. Finally, the 5th pattern loaded heavily on docosahexaenoic acid (DHA and eicosapentaenoic acid (EPA (omega-3 pattern. In crude and multivariate analysis, the sodium pattern was associated with increased risk of cataract (OR=1.97, 95%CI: 1.09-3.96. The fatty acid pattern elevated the risk of cataract (OR=1.94, 95%CI: 1.1-3.86. Antioxidant pattern was associated with a significant 79% reduced risk (2nd category compared with the 1st. Omega-3 pattern was significantly negatively associated with risk of cataract (P=0.04. CONCLUSION: These findings imply that nutrient patterns reflecting a combined consumption of nutrients might be important in the etiology of cataract. Additional studies with more efficient designs are warranted to confirm our findings.

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

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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

Nutrient Controls on Methane Emissions in a Permafrost Thaw Subarctic Peatland

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Kashi, N. N.; Perryman, C. R.; Malhotra, A.; Marek, E. A.; Giesler, R.; Varner, R. K.

2015-12-01

Permafrost peatlands in northern latitudes are large reservoirs of sequestered carbon that are vulnerable to climate change. While peatlands account for a small fraction of total global land surfaces, their potential to release sequestered carbon in response to higher temperatures is of concern. Of particular relevance is the conversion of these carbon stores into methane (CH4), a strong greenhouse gas with a global warming potential 20 times greater than that of CO2 over a 100-year time frame. Here, we explore how key nutrients impact the consumption of CH4 at the Stordalen Mire in Abisko, Sweden, a discontinuous permafrost peatland with expanding thaw over the last century. Peatland CH4 emissions are highly spatially variable due to multiple emission pathways and strong dependence on several environmental factors. Among controls on CH4 emissions, such as temperature and water table depth, primary production of wetland vegetation is also a strong factor in the variability of CH4 emissions. Plant community shifts among permafrost thaw stages subsequently change nutrient cycling and availability, which in turn impacts primary production. Early stages of permafrost thaw are mosaicked with a variety of vascular plants and mosses. We analyzed potential enzymatic activities of chitinase, glucosidase, and phosphatase as proxies for organic nitrogen, carbon, and phosphorus cycling, respectively, in tandem with potential CH4 oxidation rates. In addition, stoichiometric ratios of carbon, nitrogen, and phosphorus concentrations are used to illustrate nutrient limitation controls on CH4 oxidation rates. While CH4 emissions are low throughout initial thaw stages, highest rates of potential CH4 oxidation. These permafrost thaw-induced CH4 oxidation rates are 5 and 11 times higher, in the surface and depth of the peat profile respectively, than subsequent aerobic permafrost thaw stages. As CH4 emissions are low in intact permafrost peatlands, these high rates of potential CH4

Nutrient Control of Yeast Gametogenesis Is Mediated by TORC1, PKA and Energy Availability.

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Hilla Weidberg

2016-06-01

Full Text Available Cell fate choices are tightly controlled by the interplay between intrinsic and extrinsic signals, and gene regulatory networks. In Saccharomyces cerevisiae, the decision to enter into gametogenesis or sporulation is dictated by mating type and nutrient availability. These signals regulate the expression of the master regulator of gametogenesis, IME1. Here we describe how nutrients control IME1 expression. We find that protein kinase A (PKA and target of rapamycin complex I (TORC1 signalling mediate nutrient regulation of IME1 expression. Inhibiting both pathways is sufficient to induce IME1 expression and complete sporulation in nutrient-rich conditions. Our ability to induce sporulation under nutrient rich conditions allowed us to show that respiration and fermentation are interchangeable energy sources for IME1 transcription. Furthermore, we find that TORC1 can both promote and inhibit gametogenesis. Down-regulation of TORC1 is required to activate IME1. However, complete inactivation of TORC1 inhibits IME1 induction, indicating that an intermediate level of TORC1 signalling is required for entry into sporulation. Finally, we show that the transcriptional repressor Tup1 binds and represses the IME1 promoter when nutrients are ample, but is released from the IME1 promoter when both PKA and TORC1 are inhibited. Collectively our data demonstrate that nutrient control of entry into sporulation is mediated by a combination of energy availability, TORC1 and PKA activities that converge on the IME1 promoter.

Effect of integrated nutrient management on nut production of coconut and soil environment: a review

International Nuclear Information System (INIS)

Baloch, P.A.; Rajpar, I.

2014-01-01

With the adoption of new technology of intensive cropping with high yielding varieties, there is a considerable demand on soil for supply of nutrients. However, the native fertility of our soils is poor and cannot sustain high yields. Sustainable agricultural production incorporates the idea that natural resources should be used to generate increased output and incomes, without depleting the natural resources. The solution is application of integrated nutrient management (INM). It is the system, which envisages the use of organic wastes, biofertilisers and inorganic fertilizers in judicious combinations to sustain soil productivity. The conjunctive use of organic and inorganic sources improves soil health and helps in maximization production as it involves utilization of local sources and, hence turned to be rational, realistic and economically viable way of supply of nutrients. Coconut is a versatile tree and is the most popular home garden crop in the world. It is very beneficial for health because of its high nutrient management affects on its growth and yield characteristics to a great extent. This paper, therefore, presents a review on various aspects of INM used to improve soil environment, coconut growth and yield characters. (author)

How do controlled burns modify soil nutrients under the global change?

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E. Marcos

2013-05-01

Full Text Available The increased deposition of nutrients from the atmosphere has contributed to widespread changes in heathland ecosystems throughout Europe. Management measures, as a prescribed burning, are nowadays considered a tool with which to mitigate impacts of atmospheric nutrient loads by reducing nutrient stores in the above-ground biomass and soils. In this study we want to determine if prescribed burning is an adequate tool to maintain low nutrient levels (mainly nitrogen in heathlands in the Cantabrian Mountain which are affected by atmospheric nitrogen deposition. Three heathlands sites dominated by Calluna vulgaris were selected. In June 2005, three plots (20 x 20 m per site were established. One of them was used as a control, the second was burned and the third was burned plus fertilized with ammonium nitrate (56 kg N ha–1 yr–1 to simulated atmospheric deposition. Our results show that prescribed burning resulted in an important decrease in nitrogen and an increase in phosphorous immediately after burning. Five years later, nitrogen recovered around 80% in the burning + fertilized plot, 40% in burned plot and 77% in control plot. However, an important decreased in phosphorous were detected mainly in burning + fertilized plot (63% and burning plot (34%, while losses were lower in control plots (13%. These results suggest that heaths managed by prescribed burning will accumulate nitrogen in the long term which will affect to the surviving of this type of heathlands.

Nutrient Release, Plant Nutrition, and Potassium Leaching from Polymer-Coated Fertilizer

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Henrique Bley

Full Text Available ABSTRACT The increase in food consumption and limitations in food production areas requires improved fertilizer efficiency. Slow- or controlled-release fertilizers are an alternative for synchronizing nutrient availability with the plant demands, reducing losses to the environment. The aim of this study was to evaluate the efficacy of polymer-coated KCl compared with conventional KCl. The products were incubated in soil under controlled conditions to evaluate the time required for nutrient release. A greenhouse experiment was performed with corn plants in pots with loamy sand- or clay-textured soil types to evaluate plant nutrition and losses due to leaching. The K application rates were 0, 18, 36, and 54 mg dm-3. The pots were irrigated, and the percolated liquid was collected. The plants were harvested 30 days after sowing to quantify dry matter (DM and its K content. In the incubation study, the K release from the coated fertilizer was found to be 42 % over 154 days. The data were fit to a linear function from which a period of 315 days was estimated as required for the release of 75 % of the nutrient. Meanwhile, conventional KCl releases 85 % of the K nutrient in the first 48h. In the cultivation of plants in pots, the coating reduced K losses due to leaching in the loamy sand soil; however, only the application rate of 54 mg dm-3 promoted DM production equivalent to conventional KCl. It is possible that the need for K in the early stages of corn development was not met by a coated KCl.

Evaluating the Contributions of Atmospheric Deposition of Carbon and Other Nutrients to Nitrification in Alpine Environments

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Oldani, K. M.; Mladenov, N.; Williams, M. W.

2013-12-01

The Colorado Front Range of the Rocky Mountains contains undeveloped, barren soils, yet in this environment there is strong evidence for a microbial role in increased nitrogen (N) export. Barren soils in alpine environments are severely carbon-limited, which is the main energy source for microbial activity and sustenance of life. It has been shown that atmospheric deposition can contain high amounts of organic carbon (C). Atmospheric pollutants, dust events, and biological aerosols, such as bacteria, may be important contributors to the atmospheric organic C load. In this stage of the research we evaluated seasonal trends in the chemical composition and optical spectroscopic (fluorescence and UV-vis absorbance) signatures of snow, wet deposition, and dry deposition in an alpine environment at Niwot Ridge in the Rocky Mountains of Colorado to obtain a better understanding of the sources and chemical character of atmospheric deposition. Our results reveal a positive trend between dissolved organic carbon concentrations and calcium, nitrate and sulfate concentrations in wet and dry deposition, which may be derived from such sources as dust and urban air pollution. We also observed the presence of seasonally-variable fluorescent components that may be attributed to fluorescent pigments in bacteria. These results are relevant because atmospheric inputs of carbon and other nutrients may influence nitrification in barren, alpine soils and, ultimately, the export of nitrate to alpine watersheds.

Nitrogen and phosphorus availabilities interact to modulate leaf trait scaling relationships across six plant functional types in a controlled-environment study.

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Crous, Kristine Y; O'Sullivan, Odhran S; Zaragoza-Castells, Joana; Bloomfield, Keith J; Negrini, A Clarissa A; Meir, Patrick; Turnbull, Matthew H; Griffin, Kevin L; Atkin, Owen K

2017-08-01

Nitrogen (N) and phosphorus (P) have key roles in leaf metabolism, resulting in a strong coupling of chemical composition traits to metabolic rates in field-based studies. However, in such studies, it is difficult to disentangle the effects of nutrient supply per se on trait-trait relationships. Our study assessed how high and low N (5 mM and 0.4 mM, respectively) and P (1 mM and 2 μM, respectively) supply in 37 species from six plant functional types (PTFs) affected photosynthesis (A) and respiration (R) (in darkness and light) in a controlled environment. Low P supply increased scaling exponents (slopes) of area-based log-log A-N or R-N relationships when N supply was not limiting, whereas there was no P effect under low N supply. By contrast, scaling exponents of A-P and R-P relationships were altered by P and N supply. Neither R : A nor light inhibition of leaf R was affected by nutrient supply. Light inhibition was 26% across nutrient treatments; herbaceous species exhibited a lower degree of light inhibition than woody species. Because N and P supply modulates leaf trait-trait relationships, the next generation of terrestrial biosphere models may need to consider how limitations in N and P availability affect trait-trait relationships when predicting carbon exchange. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

A set of nutrient limitations trigger yeast cell death in a nitrogen-dependent manner during wine alcoholic fermentation.

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Camille Duc

Full Text Available Yeast cell death can occur during wine alcoholic fermentation. It is generally considered to result from ethanol stress that impacts membrane integrity. This cell death mainly occurs when grape musts processing reduces lipid availability, resulting in weaker membrane resistance to ethanol. However the mechanisms underlying cell death in these conditions remain unclear. We examined cell death occurrence considering yeast cells ability to elicit an appropriate response to a given nutrient limitation and thus survive starvation. We show here that a set of micronutrients (oleic acid, ergosterol, pantothenic acid and nicotinic acid in low, growth-restricting concentrations trigger cell death in alcoholic fermentation when nitrogen level is high. We provide evidence that nitrogen signaling is involved in cell death and that either SCH9 deletion or Tor inhibition prevent cell death in several types of micronutrient limitation. Under such limitations, yeast cells fail to acquire any stress resistance and are unable to store glycogen. Unexpectedly, transcriptome analyses did not reveal any major changes in stress genes expression, suggesting that post-transcriptional events critical for stress response were not triggered by micronutrient starvation. Our data point to the fact that yeast cell death results from yeast inability to trigger an appropriate stress response under some conditions of nutrient limitations most likely not encountered by yeast in the wild. Our conclusions provide a novel frame for considering both cell death and the management of nutrients during alcoholic fermentation.

Kinetics of growth and lipids accumulation in Chlorella vulgaris during batch heterotrophic cultivation: Effect of different nutrient limitation strategies.

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Sakarika, Myrsini; Kornaros, Michael

2017-11-01

The present study aimed at: (1) determining the effect of sulfur addition on biomass growth and (2) assessing the effect of sulfur, phosphorus and nitrogen limitation on lipid accumulation by C. vulgaris SAG 211-11b. The sulfur cellular content was more than two-fold higher under nitrogen and phosphorus limitation (0.52% and 0.54%ww -1 , respectively) compared to sulfur requirements (0.20%ww -1 ) under sulfur limiting conditions. The nitrogen needs are significantly lower (2.81-3.35%ww -1 ) when compared to other microalgae and become 23% lower under nitrogen or phosphorus limitation. The microalga exhibited substrate inhibition above 30gL -1 initial glucose concentration. Sulfur limitation had the most significant effect on lipid accumulation, resulting in maximum total lipid content of 53.43±3.93%gg DW -1 . In addition to enhancing lipid productivity, adopting the optimal nutrient limitation strategy can result in cost savings by avoiding unnecessary nutrient additions and eliminate the environmental burden due to wasted resources. Copyright © 2017 Elsevier Ltd. All rights reserved.

Protein Redox Dynamics During Light-to-Dark Transitions in Cyanobacteria and Impacts Due to Nutrient Limitation

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Aaron T Wright

2014-07-01

Full Text Available Protein redox chemistry constitutes a major void in knowledge pertaining to photoautotrophic system regulation and signaling processes. We have employed a chemical biology approach to analyze redox sensitive proteins in live Synechococcus sp. PCC 7002 cells in both light and dark periods, and to understand how cellular redox balance is disrupted during nutrient perturbation. The present work identified 300 putative redox-sensitive proteins that are involved in the generation of reductant, macromolecule synthesis, and carbon flux through central metabolic pathways, and may be involved in cell signaling and response mechanisms. Furthermore, our research suggests that dynamic redox changes in response to specific nutrient limitations, including carbon and nitrogen limitations, contribute to the regulatory changes driven by a shift from light to dark. Taken together, these results contribute to a high-level understanding of post-translational mechanisms regulating flux distributions and suggest potential metabolic engineering targets for redirecting carbon towards biofuel precursors.

Shifts in lake N: P stoichiometry and nutrient limitation driven by atmospheric nitrogen deposition

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Elser, J.J.; Andersen, T.; Baron, Jill S.; Bergstrom, A.-K.; Jansson, M.; Kyle, M.; Nydick, K.R.; Steger, L.; Hessen, D.O.

2009-01-01

Human activities have more than doubled the amount of nitrogen (N) circulating in the biosphere. One major pathway of this anthropogenic N input into ecosystems has been increased regional deposition from the atmosphere. Here we show that atmospheric N deposition increased the stoichiometric ratio of N and phosphorus (P) in lakes in Norway, Sweden, and Colorado, United States, and, as a result, patterns of ecological nutrient limitation were shifted. Under low N deposition, phytoplankton growth is generally N-limited; however, in high-N deposition lakes, phytoplankton growth is consistently P-limited. Continued anthropogenic amplification of the global N cycle will further alter ecological processes, such as biogeochemical cycling, trophic dynamics, and biological diversity, in the world's lakes, even in lakes far from direct human disturbance.

Upland and in-stream controls on baseflow nutrient dynamics in tile-drained agroecosystem watersheds

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Controls on baseflow nutrient concentrations in agroecosystems are poorly characterized in comparison with storm events. However, in landscapes with low residence times (e.g., rivers and reservoirs), baseflow nutrient concentration dynamics during sensitive timeframes can drive deleterious environm...

Hypothalamic AgRP-neurons control peripheral substrate utilization and nutrient partitioning

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Joly-Amado, Aurélie; Denis, Raphaël G P; Castel, Julien; Lacombe, Amélie; Cansell, Céline; Rouch, Claude; Kassis, Nadim; Dairou, Julien; Cani, Patrice D; Ventura-Clapier, Renée; Prola, Alexandre; Flamment, Melissa; Foufelle, Fabienne; Magnan, Christophe; Luquet, Serge

2012-01-01

Obesity-related diseases such as diabetes and dyslipidemia result from metabolic alterations including the defective conversion, storage and utilization of nutrients, but the central mechanisms that regulate this process of nutrient partitioning remain elusive. As positive regulators of feeding behaviour, agouti-related protein (AgRP) producing neurons are indispensible for the hypothalamic integration of energy balance. Here, we demonstrate a role for AgRP-neurons in the control of nutrient partitioning. We report that ablation of AgRP-neurons leads to a change in autonomic output onto liver, muscle and pancreas affecting the relative balance between lipids and carbohydrates metabolism. As a consequence, mice lacking AgRP-neurons become obese and hyperinsulinemic on regular chow but display reduced body weight gain and paradoxical improvement in glucose tolerance on high-fat diet. These results provide a direct demonstration of a role for AgRP-neurons in the coordination of efferent organ activity and nutrient partitioning, providing a mechanistic link between obesity and obesity-related disorders. PMID:22990237

Leaf life span and the mobility of "non-mobile" mineral nutrients - the case of boron in conifers

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Pedro J. Aphalo; Anna W. Schoettle; Tarja Lehto

2002-01-01

Nutrient conservation is considered important for the adaptation of plants to infertile environments. The importance of leaf life spans in controlling mean residence time of nutrients in plants has usually been analyzed in relation to nutrients that can be retranslocated within the plant. Longer leaf life spans increase the mean residence time of all mineral...

Wildfire Effects on In-stream Nutrient Processing and Hydrologic Transport

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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.

Global comparison reveals biogenic weathering as driven by nutrient limitation at ecosystem scale

Science.gov (United States)

Boy, Jens; Godoy, Roberto; Dechene, Annika; Shibistova, Olga; Amir, Hamid; Iskandar, Issi; Fogliano, Bruno; Boy, Diana; McCulloch, Robert; Andrino, Alberto; Gschwendtner, Silvia; Marin, Cesar; Sauheitl, Leopold; Dultz, Stefan; Mikutta, Robert; Guggenberger, Georg

2017-04-01

A substantial contribution of biogenic weathering in ecosystem nutrition, especially by symbiotic microorganisms, has often been proposed, but large-scale in vivo studies are still missing. Here we compare a set of ecosystems spanning from the Antarctic to tropical forests for their potential biogenic weathering and its drivers. To address biogenic weathering rates, we installed mineral mesocosms only accessible for bacteria and fungi for up to 4 years, which contained freshly broken and defined nutrient-baring minerals in soil A horizons of ecosystems along a gradient of soil development differing in climate and plant species communities. Alterations of the buried minerals were analyzed by grid-intersection, confocal lascer scanning microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy on the surface and on thin sections. On selected sites, carbon fluxes were tracked by 13C labeling, and microbial community was identified by DNA sequencing. In young ecosystems (protosoils) biogenic weathering is almost absent and starts after first carbon accumulation by aeolian (later litter) inputs and is mainly performed by bacteria. With ongoing soil development and appearance of symbiotic (mycorrhized) plants, nutrient availability in soil increasingly drove biogenic weathering, and fungi became the far more important players than bacteria. We found a close relation between fungal biogenic weathering and available potassium across all 16 forested sites in the study, regardless of the dominant mycorrhiza type (AM or EM), climate, and plant-species composition. We conclude that nutrient limitations at ecosystem scale are generally counteracted by adapted fungal biogenic weathering. The close relation between fungal weathering and plant-available nutrients over a large range of severely contrasting ecosystems points towards a direct energetic support of these weathering processes by the photoautotrophic community, making biogenic weathering a

Potential Foraging Decisions by a Desert Ungulate to Balance Water and Nutrient Intake in a Water-Stressed Environment.

Science.gov (United States)

Gedir, Jay V; Cain, James W; Krausman, Paul R; Allen, Jamison D; Duff, Glenn C; Morgart, John R

2016-01-01

Arid climates have unpredictable precipitation patterns, and wildlife managers often provide supplemental water to help desert ungulates endure the hottest, driest periods. When surface water is unavailable, the only source of water for ungulates comes from the forage they consume, and they must make resourceful foraging decisions to meet their requirements. We compared two desert bighorn sheep (Ovis canadensis nelsoni) populations in Arizona, USA: a treatment population with supplemental water removed during treatment, and a control population. We examined whether sheep altered their seasonal diets without supplemental water. We calculated water and nutrient intake and metabolic water production from dry matter intake and forage moisture and nitrogen content, to determine whether sheep could meet their seasonal daily water and nutrient requirements solely from forage. Diets of sheep were higher in protein (all seasons) and moisture (autumn and winter) during treatment compared to pretreatment. During treatment, sheep diet composition was similar between the treatment and control populations, which suggests, under the climatic conditions of this study, water removal did not influence sheep diets. We estimated that under drought conditions, without any surface water available (although small ephemeral potholes would contain water after rains), female and male sheep would be unable to meet their daily water requirements in all seasons, except winter, when reproductive females had a nitrogen deficit. We determined that sheep could achieve water and nutrient balances in all seasons by shifting their total diet proportions by 8-55% from lower to higher moisture and nitrogen forage species. We elucidate how seasonal forage quality and foraging decisions by desert ungulates allow them to cope with their xeric and uncertain environment, and suggest that, with the forage conditions observed in our study area during this study period, providing supplemental water during

Potential foraging decisions by a desert ungulate to balance water and nutrient intake in a water-stressed environment

Science.gov (United States)

Gedir, Jay V.; Cain, James W.; Krausman, Paul R.; Allen, Jamison D.; Duff, Glenn C.; Morgart, John R.

2016-01-01

Arid climates have unpredictable precipitation patterns, and wildlife managers often provide supplemental water to help desert ungulates endure the hottest, driest periods. When surface water is unavailable, the only source of water for ungulates comes from the forage they consume, and they must make resourceful foraging decisions to meet their requirements. We compared two desert bighorn sheep (Ovis canadensis nelsoni) populations in Arizona, USA: a treatment population with supplemental water removed during treatment, and a control population. We examined whether sheep altered their seasonal diets without supplemental water. We calculated water and nutrient intake and metabolic water production from dry matter intake and forage moisture and nitrogen content, to determine whether sheep could meet their seasonal daily water and nutrient requirements solely from forage. Diets of sheep were higher in protein (all seasons) and moisture (autumn and winter) during treatment compared to pretreatment. During treatment, sheep diet composition was similar between the treatment and control populations, which suggests, under the climatic conditions of this study, water removal did not influence sheep diets. We estimated that under drought conditions, without any surface water available (although small ephemeral potholes would contain water after rains), female and male sheep would be unable to meet their daily water requirements in all seasons, except winter, when reproductive females had a nitrogen deficit. We determined that sheep could achieve water and nutrient balances in all seasons by shifting their total diet proportions by 8–55% from lower to higher moisture and nitrogen forage species. We elucidate how seasonal forage quality and foraging decisions by desert ungulates allow them to cope with their xeric and uncertain environment, and suggest that, with the forage conditions observed in our study area during this study period, providing supplemental water during

Potential Foraging Decisions by a Desert Ungulate to Balance Water and Nutrient Intake in a Water-Stressed Environment.

Directory of Open Access Journals (Sweden)

Jay V Gedir

Full Text Available Arid climates have unpredictable precipitation patterns, and wildlife managers often provide supplemental water to help desert ungulates endure the hottest, driest periods. When surface water is unavailable, the only source of water for ungulates comes from the forage they consume, and they must make resourceful foraging decisions to meet their requirements. We compared two desert bighorn sheep (Ovis canadensis nelsoni populations in Arizona, USA: a treatment population with supplemental water removed during treatment, and a control population. We examined whether sheep altered their seasonal diets without supplemental water. We calculated water and nutrient intake and metabolic water production from dry matter intake and forage moisture and nitrogen content, to determine whether sheep could meet their seasonal daily water and nutrient requirements solely from forage. Diets of sheep were higher in protein (all seasons and moisture (autumn and winter during treatment compared to pretreatment. During treatment, sheep diet composition was similar between the treatment and control populations, which suggests, under the climatic conditions of this study, water removal did not influence sheep diets. We estimated that under drought conditions, without any surface water available (although small ephemeral potholes would contain water after rains, female and male sheep would be unable to meet their daily water requirements in all seasons, except winter, when reproductive females had a nitrogen deficit. We determined that sheep could achieve water and nutrient balances in all seasons by shifting their total diet proportions by 8-55% from lower to higher moisture and nitrogen forage species. We elucidate how seasonal forage quality and foraging decisions by desert ungulates allow them to cope with their xeric and uncertain environment, and suggest that, with the forage conditions observed in our study area during this study period, providing supplemental

Limiting nutrient emission from a cut rose closed system by high-flux irrigation and low nutrient concentrations?

NARCIS (Netherlands)

Baas, R.; Berg, van der D.

2004-01-01

A two-year project was aimed at decreasing nutrient emission from closed nutrient systems by using high irrigation rates in order to allow lower EC levels in the presence of accumulated Na and Cl. Experimental variables were growing media, irrigation frequencies, EC and NaCl concentrations for cut

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

The role of grazing in nutrient-rich areas of the open sea

International Nuclear Information System (INIS)

Frost, B.W.

1991-01-01

No single factor accounts fully for the persistently low phytoplankton stocks in the nutrient-rich areas of the open sea. However, grazing plays the necessary role of consuming phytoplankton produced in excess of losses due to physical processes and sinking. Without grazing, even if specific growth rate of the phytoplankton is less than optimal for the prevailing light and temperature conditions, as might be so under limitation by a trace nutrient such as Fe, the phytoplankton stock would still accumulate with attendant depletion of nutrients. Observations during spring and summer in the open subarctic Pacific argue against limitation of phytoplankton growth to the point where phytoplankton stock could not increase in the absence of grazing. An ecosystem process model of the phytoplankton-grazer interaction suggests that two processes - grazing control of phytoplankton stock and preferential utilization of NH 4 by the phytoplankton - are sufficient to explain the continuously low phytoplankton stock and high concentrations of macronutrients. However, the grazing control may be exerted on a phytoplankton assemblage structured by Fe limitation. In particular, the intrinsic growth rates of potentially fast-growing diatoms seem to be depressed in the open subarctic Pacific. These conditions probably apply to two other nutrient-rich areas of the open sea, the Pacific equatorial upwelling region and the subantarctic circumpolar ocean, although in the latter region light limitation of phytoplankton growth may be more severe and silica limitation may influence the specific composition of the phytoplankton assemblage

Nutrient losses from cattle co-digestate slurry during storage

Directory of Open Access Journals (Sweden)

Francesca Perazzolo

2016-06-01

Full Text Available Among environmental issues related to intensive livestock activity, emissions to air from manure management are of increasing concern. Thus the knowledge of the effect of treatment application on subsequent emissions from manure is required to assess the environment impact of management solutions. This work addresses the effect of anaerobic digestion and phase separation on emissions during storage by studying nitrogen losses from lab-scale stores and field pilot-scale stores of a co-digestate cattle slurry and its respective separated fractions. Lab-scale experiment was carried in temperature-controlled room where each fraction (untreated, separated liquid and separated solid was stored in duplicate for a period of 32 days in 30 L vessel. Pilot-scale experiment was carried out both during the cold season and during warm season for 90 days of storage. In both experimentations samples of the manure were analysed periodically for total Kjeldahl nitrogen (TKN, total ammonia nitrogen, dry matter and volatile solids and pH. These analyses allow estimating nitrogen losses in different storage conditions. Effects of mechanical separation and season were assessed by ANOVA (Wilcoxon test, P<0.05. In temperature controlled conditions nitrogen losses measured account for 13% and 26% of TKN for unseparated and separated slurries respectively. In field conditions during cold season nutrient losses were limited. On average unseparated and separated slurries lost respectively 6.8% and 12.6% of their initial TKN content. Much higher were the TKN losses from the slurries examined in warm season where losses raised up to 40% of the initial TKN content. Generally mechanical separation increases nutrient losses, but the differences were not significant in field conditions. The results highlighted that nutrient losses, in particular the nitrogen ones, can be considerable especially during summer storage. The latter, in case of separated slurries, are mainly related

Nutrient Infiltrate Concentrations from Three Permeable Pavement Types

Science.gov (United States)

While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types have on nutrient concentrations present in stormwater runoff are limited. In 2009, the U.S. EPA constructed a 0.4-ha...

Adaptation of Bacillus subtilis carbon core metabolism to simultaneous nutrient limitation and osmotic challenge : a multi-omics perspective

NARCIS (Netherlands)

Kohlstedt, Michael; Sappa, Praveen K; Meyer, Hanna; Maaß, Sandra; Zaprasis, Adrienne; Hoffmann, Tamara; Becker, Judith; Steil, Leif; Hecker, Michael; van Dijl, Jan Maarten; Lalk, Michael; Mäder, Ulrike; Stülke, Jörg; Bremer, Erhard; Völker, Uwe; Wittmann, Christoph

The Gram-positive bacterium Bacillus subtilis encounters nutrient limitations and osmotic stress in its natural soil ecosystem. To ensure survival and sustain growth, highly integrated adaptive responses are required. Here, we investigated the system-wide response of B.subtilis to different,

[Effects of neighbor competition on growth, fine root morphology and distribution of Schima superba and Cunninghamia lanceolata in different nutrient environments].

Science.gov (United States)

Yao, Jia Bao; Chu, Xiu Li; Zhou, Zhi Chun; Tong, Jian She; Wang, Hui; Yu, Jia Zhong

2017-05-18

Taking Schima superba and Cunninghamia lanceolata as test materials, a pot experiment was conducted to simulate the heterogeneous and homogeneous forest soil nutrient environments, and design three planting modes including single plant, two-strain pure plant and two-strain mixed ones to reason the promotion in mixed S. superba and C. lanceolata plantation and the competitive advantage of S. superba. Results showed that compared with the homogeneous nutrient environment, both S. superba and C. lanceolata had the higher seedling height and dry matter accumulation, when mixed in the heterogeneous nutrient environment, S. superba displayed the obviously competitive advantage, which related to its root plasticity. The fine root of S. superba mixed in each diameter class showed a lot of hyperplasia, and the root total length, surface area and volume of which were 80%-180% higher than that of C. lanceolata. S. superba took the advantage of the compensatory growth strategy of vertical direction in fine roots, namely, they still multiplied to gain greater competitive advantage in low nutrient patches, besides occupying eutrophic surface. The different soil colonization and niche differentiation in fine root of S. superba and C. lanceolata alleviated the strong competition for nutrients of the roots of the two species, and improved the mixed-plantation production. Pure plantation of S. superba harvested the lower yield, which due to the root self-recognition inhibited the growth of root system. Fine roots staggered and evenly distributed on the space might be a reason for stable structure of pure S. superba plantation. So, it was recommended that block surface layer soil preparation and fertilization are used to improve the soil nutrient distribution, and the mixed plantation is constructed to promote the growth of S. superba and C. lanceolata, at the same time, the stand density is regulated to promote tree growth for the pure artificial S. superba plantation which had

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.

Nutrient cycle benchmarks for earth system land model

Science.gov (United States)

Zhu, Q.; Riley, W. J.; Tang, J.; Zhao, L.

2017-12-01

Projecting future biosphere-climate feedbacks using Earth system models (ESMs) relies heavily on robust modeling of land surface carbon dynamics. More importantly, soil nutrient (particularly, nitrogen (N) and phosphorus (P)) dynamics strongly modulate carbon dynamics, such as plant sequestration of atmospheric CO2. Prevailing ESM land models all consider nitrogen as a potentially limiting nutrient, and several consider phosphorus. However, including nutrient cycle processes in ESM land models potentially introduces large uncertainties that could be identified and addressed by improved observational constraints. We describe the development of two nutrient cycle benchmarks for ESM land models: (1) nutrient partitioning between plants and soil microbes inferred from 15N and 33P tracers studies and (2) nutrient limitation effects on carbon cycle informed by long-term fertilization experiments. We used these benchmarks to evaluate critical hypotheses regarding nutrient cycling and their representation in ESMs. We found that a mechanistic representation of plant-microbe nutrient competition based on relevant functional traits best reproduced observed plant-microbe nutrient partitioning. We also found that for multiple-nutrient models (i.e., N and P), application of Liebig's law of the minimum is often inaccurate. Rather, the Multiple Nutrient Limitation (MNL) concept better reproduces observed carbon-nutrient interactions.

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.

Game-based training environment for nuclear plant control room

International Nuclear Information System (INIS)

Hung Tamin; Sun Tienlung; Yang Chihwei; Yang Lichen; Cheng Tsungchieh; Wang Jyhgang

2011-01-01

Nuclear power plant's safety is very important problem. In this very conscientious environment if operator has a little mistake, they may threaten with many people influence their safety. Therefore, operating training of control room is very important. However, the operator training is in limited space and time. Each operator must go to simulative control room do some training. If we can let each trainee having more time to do training and does not go to simulative control room. It may have some advantages for trainee. Moreover, in the traditional training ways, each operator may through the video, teaching manual or through the experienced instructor to learn the knowledge. This training way may let operator feel bored and stressful. So, in this paper aims, we hope utilizing virtual reality technology developing a game-based virtual training environment of control room. Finally, we will use presence questionnaire evaluating realism and feasibility of our virtual training environment. Expecting this initial concept of game-based virtual training environment can attract trainees having more learning motivation to do training in off-hour. (author)

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.

Effect of HIV/AIDS on the control environment.

Science.gov (United States)

Coetzee, Philna

2006-07-01

The management of organizations is responsible for risk management and control systems. HIV/AIDS could be a great threat in the achievement of strategic business objectives, implicating a great concern for management. Management needs to understand this possible risk. This study aims to identify the effect that HIV/AIDS could have on the different elements of the control environment. The archival research method was used. It was established that no formal research was conducted to date on the effect of HIV/AIDS on the control environment as a whole. Various studies have included the effect of HIV/AIDS on certain factors of the control environment. These studies will be discussed briefly to identify relevant findings. The study indicated that the disease could affect various aspects of the control environment, namely: competency of the workforce (e.g. productivity, quality of work, absenteeism, loss of skills and knowledge, training and recruitment, etc.); organizational structure (e.g. increase use of technology labour, disruption of processes, level of employees affected by the disease); human resource (HR) policies and practices (e.g. legislation applicable, prevention and awareness programmes, compensation and benefits). Research limitation: HIV/AIDS is a relatively new potential risk to organizations. Knowledge of the disease is limited. HIV/AIDS is also a very sensitive issue as people fear the disease and do not like to discuss its existence. Government determined that it should be a non-notifiable disease and the disease is currently greatly stigmatized. The databases of companies investigated by other research studies were not developed to gather all the relevant information. Management should be aware that HIV/AIDS poses a possible risk to organizations. Data on the effect of HIV/AIDS should be gathered and used in the decision-making process on how to manage this risk. To be able to fulfil this duty, management first has to determine: whether HIV/AIDS is

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.

An Energy-Based Limit State Function for Estimation of Structural Reliability in Shock Environments

Directory of Open Access Journals (Sweden)

Michael A. Guthrie

2013-01-01

Full Text Available limit state function is developed for the estimation of structural reliability in shock environments. This limit state function uses peak modal strain energies to characterize environmental severity and modal strain energies at failure to characterize the structural capacity. The Hasofer-Lind reliability index is briefly reviewed and its computation for the energy-based limit state function is discussed. Applications to two degree of freedom mass-spring systems and to a simple finite element model are considered. For these examples, computation of the reliability index requires little effort beyond a modal analysis, but still accounts for relevant uncertainties in both the structure and environment. For both examples, the reliability index is observed to agree well with the results of Monte Carlo analysis. In situations where fast, qualitative comparison of several candidate designs is required, the reliability index based on the proposed limit state function provides an attractive metric which can be used to compare and control reliability.

Feed-Forward control of water and nutrient supply in greenhouse horticulture: development of a system

NARCIS (Netherlands)

Elings, A.; Heinen, M.; Werner, B.E.; Visser, de P.; Boogaard, van den H.A.G.M.; Gieling, T.H.; Marcelis, L.F.M.

2004-01-01

Minimisation of nutrient and water loss to the environment, prediction and planning of production and product quality, such that they meet the demands of customers, and increased financial return are some of the goals of current greenhouse horticulture. This requires an integrated system for

Evolving Robot Controllers for Structured Environments Through Environment Decomposition

DEFF Research Database (Denmark)

Moreno, Rodrigo; Faiña, Andres; Støy, Kasper

2015-01-01

In this paper we aim to develop a controller that allows a robot to traverse an structured environment. The approach we use is to decompose the environment into simple sub-environments that we use as basis for evolving the controller. Specifically, we decompose a narrow corridor environment...... environments and that the order in which the decomposed sub-environments are presented in sequence impacts the performance of the evolutionary algorithm....

River Metabolism and Nutrient Cycling at the Point Scale: Insights from In Situ Sensors in Benthic Chambers

Science.gov (United States)

Cohen, M. J.; Reijo, C. J.; Hensley, R. T.

2017-12-01

Riverine processing of nutrients and carbon is a local process, subject to heterogeneity in sediment, biotic, insolation, and flow velocity drivers. Measurements at the reach scale aggregate across riverscapes, limiting their utility for enumerating these drivers, and thus for scaling to river networks. Using a combination of in situ sensors that sample water chemistry at high temporal resolution and open benthic chambers that isolate the biogeochemical impacts of a small footprint of benthic surface area, we explored controls on metabolism and nutrient cycling. We specifically sought to answer two questions. First, what are the controls on primary production, with a particular emphasis on the relative roles of light vs. nutrient limitation? Second, what are the pathways of nutrient retention, and do the reaction kinetics of these different pathways differ? We demonstrate the considerable utility of these benthic chambers, reasoning that they provide experimental units for river processes that are not attainable at the reach or network scale. Specifically, in addition to their ability to sample the heterogeneity of the river bed as well as observe nutrient depletion to create concentrations well below ambient levels, they enable manipulative experiments (e.g., nutrient enrichment, light reduction, grazer adjustments) while retaining key elements of the natural system. Across several of Florida's spring-fed river sites, our results strongly support the primacy of light limitation of primary production, with very little evidence of any incremental effects of nutrient enrichment. Nutrient depletion assays further support the dominance of two N retention mechanisms (denitrification and assimilation), the kinetics of which differ markedly, with denitrification exhibiting nearly first-order reactions, and assimilation following zero-order or Michaelis-Menten kinetics over the range of observed concentrations. This latter result helps explain the absence of strong

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.

Production of polyhydroxybutyrates and carbohydrates in a mixed cyanobacterial culture: Effect of nutrients limitation and photoperiods.

Science.gov (United States)

Arias, Dulce María; Uggetti, Enrica; García-Galán, María Jesús; García, Joan

2018-05-25

In the present study, different photoperiods and nutritional conditions were applied to a mixed wastewater-borne cyanobacterial culture in order to enhance the intracellular accumulation of polyhydroxybutyrates (PHBs) and carbohydrates. Two different experimental set-ups were used. In the first, the culture was permanently exposed to illumination, while in the second it was submitted to light/dark alternation (12 h cycles). In both cases, two different nutritional regimes were also evaluated, N-limitation and P-limitation. Results showed that the highest PHB concentration (104 mg L -1 ) was achieved under P limited conditions and permanent illumination, whereas the highest carbohydrate concentration (838 mg L -1 ) was obtained under N limited condition and light/dark alternation. With regard to bioplastics and biofuel generation, this study demonstrates that the accumulation of PHBs (bioplastics) and carbohydrates (potential biofuel substrate) is favored in wastewater-borne cyanobacteria under conditions where nutrients are limited. Copyright © 2018 Elsevier B.V. All rights reserved.

40 CFR Table 4 to Subpart Xxxx of... - Operating Limits for Puncture Sealant Application Control Devices

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Operating Limits for Puncture Sealant Application Control Devices 4 Table 4 to Subpart XXXX of Part 63 Protection of Environment ENVIRONMENTAL... Manufacturing Pt. 63, Subpt. XXXX, Table 4 Table 4 to Subpart XXXX of Part 63—Operating Limits for Puncture...

Reactor limit control system

International Nuclear Information System (INIS)

Rubbel, F.E.

1982-01-01

The very extensive use of limitations in the operational field between protection system and closed-loop controls is an important feature of German understanding of operational safety. The design of limitations is based on very large activities in the computational field but mostly on the high level of the plant-wide own commissioning experience of a turnkey contractor. Limitations combine intelligence features of closed-loop controls with the high availability of protection systems. (orig.)

Phosphorus: a limiting nutrient for humanity?

Science.gov (United States)

Elser, James J

2012-12-01

Phosphorus is a chemical element that is essential to life because of its role in numerous key molecules, including DNA and RNA; indeed, organisms require large amounts of P to grow rapidly. However, the supply of P from the environment is often limiting to production, including to crops. Thus, large amounts of P are mined annually to produce fertilizer that is applied in support of the 'Green Revolution.' However, much of this fertilizer eventually ends up in rivers, lakes and oceans where it causes costly eutrophication. Furthermore, given increasing human population, expanding meat consumption, and proliferating bioenergy pressures, concerns have recently been raised about the long-term geological, economic, and geopolitical viability of mined P for fertilizer production. Together, these issues highlight the non-sustainable nature of current human P use. To achieve P sustainability, farms need to become more efficient in how they use P while society as a whole must develop technologies and practices to recycle P from the food chain. Such large-scale changes will probably require a radical restructuring of the entire food system, highlighting the need for prompt but sustained action. Copyright © 2012 Elsevier Ltd. All rights reserved.

Can nutrient limitations explain low and declining white spruce growth near the Arctic treeline in the eastern Brooks Range, Alaska?

Science.gov (United States)

Ellison, S.; Sullivan, P. F.

2014-12-01

The position of the Arctic treeline is of critical importance for global carbon cycling and surface energy budgets. However, controls on tree growth at treeline remain uncertain. In the Alaskan Brooks Range, 20th century warming has caused varying growth responses among treeline trees, with trees in the west responding positively, while trees in the east have responded negatively. The prevailing explanation of this trend ascribes the negative growth response to warming-induced drought stress in the eastern Brooks Range. However, recent measurements of carbon isotope discrimination in tree rings, xylem sap flow and needle gas exchange suggest that drought stress cannot explain these regional growth declines. Additionally, evidence from the western Brooks Range suggests that nutrient availability, rather than drought stress, may be the proximate control on tree growth. In this study, we investigated the hypothesis that low and declining growth of eastern Brooks Range trees is due to low and declining soil nutrient availability, which may continue to decrease with climate change as soils become drier and microbial activity declines. We compared microclimate, tree performance, and a wide range of proxies for soil nutrient availability in four watersheds along a west-east transect in the Brooks Range during the growing seasons of 2013 and 2014. We hypothesized that soil nutrient availability would track closely with the strong west-east precipitation gradient, with higher rainfall and greater soil nutrient availability in the western Brooks Range. We expected to find that soil water contents in the west are near optimum for nitrogen mineralization, while those in the east are below optimum. Needle nitrogen concentration, net photosynthesis, branch extension growth, and growth in the main stem are expected to decline with the hypothesized decrease in soil nutrient availability. The results of our study will elucidate the current controls on growth of trees near the

Root foraging increases performance of the clonal plant Potentilla reptans in heterogeneous nutrient environments.

Science.gov (United States)

Wang, Zhengwen; van Kleunen, Mark; During, Heinjo J; Werger, Marinus J A

2013-01-01

Plastic root-foraging responses have been widely recognized as an important strategy for plants to explore heterogeneously distributed resources. However, the benefits and costs of root foraging have received little attention. In a greenhouse experiment, we grew pairs of connected ramets of 22 genotypes of the stoloniferous plant Potentilla reptans in paired pots, between which the contrast in nutrient availability was set as null, medium and high, but with the total nutrient amount kept the same. We calculated root-foraging intensity of each individual ramet pair as the difference in root mass between paired ramets divided by the total root mass. For each genotype, we then calculated root-foraging ability as the slope of the regression of root-foraging intensity against patch contrast. For all genotypes, root-foraging intensity increased with patch contrast and the total biomass and number of offspring ramets were lowest at high patch contrast. Among genotypes, root-foraging intensity was positively related to production of offspring ramets and biomass in the high patch-contrast treatment, which indicates an evolutionary benefit of root foraging in heterogeneous environments. However, we found no significant evidence that the ability of plastic foraging imposes costs under homogeneous conditions (i.e. when foraging is not needed). Our results show that plants of P. reptans adjust their root-foraging intensity according to patch contrast. Moreover, the results show that the root foraging has an evolutionary advantage in heterogeneous environments, while costs of having the ability of plastic root foraging were absent or very small.

40 CFR Table 1 to Subpart Ssss of... - Operating Limits if Using Add-on Control Devices and Capture System

Science.gov (United States)

2010-07-01

... Using Add-on Control Devices and Capture System If you are required to comply with operating limits by... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Operating Limits if Using Add-on Control Devices and Capture System 1 Table 1 to Subpart SSSS of Part 63 Protection of Environment...

40 CFR Table 1 to Subpart Jjjj of... - Operating Limits if Using Add-On Control Devices and Capture System

Science.gov (United States)

2010-07-01

... Limits if Using Add-On Control Devices and Capture System If you are required to comply with operating... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Operating Limits if Using Add-On Control Devices and Capture System 1 Table 1 to Subpart JJJJ of Part 63 Protection of Environment...

Impact of protected mealtimes on ward mealtime environment, patient experience and nutrient intake in hospitalised patients.

Science.gov (United States)

Hickson, M; Connolly, A; Whelan, K

2011-08-01

Malnutrition is a common problem in hospitalised inpatients, resulting in a range of negative clinical, patient-centred and economic sequelae. Protected mealtimes (PM) aim to enhance the quality of the mealtime experience and maximise nutrient intake in hospitalised patients. The present study aimed to measure mealtime environment, patient experience and nutrient intake before and after the implementation of PM.   PM were implemented in a large teaching hospital through a range of different approaches. Direct observations were used to assess ward-level mealtime environment (e.g. dining room use, removal of distractions) (40 versus 34 wards) and individual patient experience (e.g. assistance with eating, visitors present) (253 versus 237 patients), and nutrient intake was assessed with a weighed food intake at lunch (39 versus 60 patients) at baseline and after the implementation of PM, respectively. Mealtime experience showed improvements in three objectives: more patients were monitored using food/fluid charts (32% versus 43%, P = 0.02), more were offered the opportunity to wash hands (30% versus 40%, P = 0.03) and more were served meals at uncluttered tables (54% versus 64%, P = 0.04). There was no difference in the number of patients experiencing mealtime interruptions (32% versus 25%, P = 0.14). There was no difference in energy intake (1088 versus 837 kJ, P = 0.25) and a decrease in protein intake (14.0 versus 7.5 g, P = 0.04) after PM. Only minor improvements in mealtime experience were made after the implementation of PM and so it is not unexpected that macronutrient intake did not improve. The implementation of PM needs to be evaluated to ensure improvements in mealtime experience are made such that measurable improvements in nutritional and clinical outcomes ensue. © 2011 The Authors. Journal of Human Nutrition and Dietetics © 2011 The British Dietetic Association Ltd.

Nutrient management regulations in The Netherlands

NARCIS (Netherlands)

Schröder, J.J.; Neeteson, J.J.

2008-01-01

The application of nutrients affect the quality of the environment which justifies the consideration of regulations regarding their use in agriculture. In the early 1990s The Netherlands decided to use the indicator `nutrient surplus at farm level¿ as the basis for a regulation which was called the

40 CFR Table 2 to Subpart Oooo of... - Operating Limits if Using Add-On Control Devices and Capture System

Science.gov (United States)

2010-07-01

... OOOO of Part 63—Operating Limits if Using Add-On Control Devices and Capture System If you are required... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Operating Limits if Using Add-On Control Devices and Capture System 2 Table 2 to Subpart OOOO of Part 63 Protection of Environment...

Effects of growth rate, cell size, motion, and elemental stoichiometry on nutrient transport kinetics.

Science.gov (United States)

Flynn, Kevin J; Skibinski, David O F; Lindemann, Christian

2018-04-01

Nutrient acquisition is a critical determinant for the competitive advantage for auto- and osmohetero- trophs alike. Nutrient limited growth is commonly described on a whole cell basis through reference to a maximum growth rate (Gmax) and a half-saturation constant (KG). This empirical application of a Michaelis-Menten like description ignores the multiple underlying feedbacks between physiology contributing to growth, cell size, elemental stoichiometry and cell motion. Here we explore these relationships with reference to the kinetics of the nutrient transporter protein, the transporter rate density at the cell surface (TRD; potential transport rate per unit plasma-membrane area), and diffusion gradients. While the half saturation value for the limiting nutrient increases rapidly with cell size, significant mitigation is afforded by cell motion (swimming or sedimentation), and by decreasing the cellular carbon density. There is thus potential for high vacuolation and high sedimentation rates in diatoms to significantly decrease KG and increase species competitive advantage. Our results also suggest that Gmax for larger non-diatom protists may be constrained by rates of nutrient transport. For a given carbon density, cell size and TRD, the value of Gmax/KG remains constant. This implies that species or strains with a lower Gmax might coincidentally have a competitive advantage under nutrient limited conditions as they also express lower values of KG. The ability of cells to modulate the TRD according to their nutritional status, and hence change the instantaneous maximum transport rate, has a very marked effect upon transport and growth kinetics. Analyses and dynamic models that do not consider such modulation will inevitably fail to properly reflect competitive advantage in nutrient acquisition. This has important implications for the accurate representation and predictive capabilities of model applications, in particular in a changing environment.

Role of nutrient limitation and stationary-phase existence in Klebsiella pneumoniae biofilm resistance to ampicillin and ciprofloxacin.

Science.gov (United States)

Anderl, Jeff N; Zahller, Jeff; Roe, Frank; Stewart, Philip S

2003-04-01

Biofilms formed by Klebsiella pneumoniae resisted killing during prolonged exposure to ampicillin or ciprofloxacin even though these agents have been shown to penetrate bacterial aggregates. Bacteria dispersed from biofilms into medium quickly regained most of their susceptibility. Experiments with free-floating bacteria showed that stationary-phase bacteria were protected from killing by either antibiotic, especially when the test was performed in medium lacking carbon and nitrogen sources. These results suggested that the antibiotic tolerance of biofilm bacteria could be explained by nutrient limitation in the biofilm leading to stationary-phase existence of at least some of the cells in the biofilm. This mechanism was supported by experimental characterization of nutrient availability and growth status in biofilms. The average specific growth rate of bacteria in biofilms was only 0.032 h(-1) compared to the specific growth rate of planktonic bacteria of 0.59 h(-1) measured in the same medium. Glucose did not penetrate all the way through the biofilm, and oxygen was shown to penetrate only into the upper 100 micro m. The specific catalase activity was elevated in biofilm bacteria to a level similar to that of stationary-phase planktonic cells. Transmission electron microscopy revealed that bacteria were affected by ampicillin near the periphery of the biofilm but were not affected in the interior. Taken together, these results indicate that K. pneumoniae in this system experience nutrient limitation locally within the biofilm, leading to zones in which the bacteria enter stationary phase and are growing slowly or not at all. In these inactive regions, bacteria are less susceptible to killing by antibiotics.

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)

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

Inherent limitations of fixed time servo-controlled radiometric calorimetry

International Nuclear Information System (INIS)

Wetzel, J.R.; Duff, M.F.; Lemming, J.F.

1987-01-01

There has been some interest in low precision, short run time calorimetry measurements. This type of calorimetry measurement has been proposed for use when high precision measurements are not required, for example, to screen scrap containers to determine if there is enough material to be measured more accurately of for confirmatory measurements that only require low precision results. The equipment needed to make these measurements is a servo-controlled calorimeter with a sample preequilibration bath. The preequilibration bath temperature is set to the internal temperature of the calorimeter running at a fixed servo-controlled wattage level. The sample power value is determined at a fixed time form the sample loading into the calorimeter. There are some limitations and areas of uncertainties in the use of data obtained by this method. Data collected under controlled conditions demonstrate the limitations. Sample packaging, preequilibration time, and item wattage were chosen as the variables most likely to be encountered in a plant environment

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 ...

Upland and in-stream controls on baseflow nutrient dynamics in tile-drained agroecosystem watersheds

Science.gov (United States)

Ford, William I.; King, Kevin; Williams, Mark R.

2018-01-01

In landscapes with low residence times (e.g., rivers and reservoirs), baseflow nutrient concentration dynamics during sensitive timeframes can contribute to deleterious environmental conditions downstream. This study assessed upland and in-stream controls on baseflow nutrient concentrations in a low-gradient, tile-drained agroecosystem watershed. We conducted time-series analysis using Empirical mode decomposition of seven decade-long nutrient concentration time-series in the agricultural Upper Big Walnut Creek watershed (Ohio, USA). Four tributaries of varying drainage areas and three main-stem sites were monitored, and nutrient grab samples were collected weekly from 2006 to 2016 and analyzed for dissolved reactive phosphorus (DRP), nitrate-nitrogen (NO3-N), total nitrogen (TN), and total phosphorus (TP). Statistically significant seasonal fluctuations were compared with seasonality of baseflow, watershed characteristics (e.g., tile-drain density), and in-stream water quality parameters (pH, DO, temperature). Findings point to statistically significant seasonality of all parameters with peak P concentrations in summer and peak N in late winter-early spring. Results suggest that upland processes exert strong control on DRP concentrations in the winter and spring months, while coupled upland and in-stream conditions control watershed baseflow DRP concentrations during summer and early fall. Conversely, upland flow sources driving streamflow exert strong control on baseflow NO3-N, and in-stream attenuation through transient and permanent pathways impacts the magnitude of removal. Regarding TN and TP, we found that TN was governed by NO3-N, while TP was governed by DRP in summer and fluvial erosion of P-rich benthic sediments during higher baseflow conditions. Findings of the study highlight the importance of coupled in-stream and upland management for mitigating eutrophic conditions during environmentally sensitive timeframes.

Integrated real-time control strategy in multi-tank A2O process for biological nutrient removal treating real domestic wastewater

Directory of Open Access Journals (Sweden)

Saad Abualhail

2017-02-01

Full Text Available An integrated real-time anaerobic–anoxic/oxic (A2O operated with multi-tank called IMT–A2O process was designed and operated with fluctuating influent loads for biological nutrient removal for treating real domestic wastewater. IMT–A2O process, a “phased isolation tank” technology, varies both aeration pattern and flow path in a continuous flow multi-tank system to force fluctuation of organic and nutrient concentrations in process reactors. Using an eight-phase cycle, desired biochemical transformations, are accomplished at different times in the same tank. On-line sensors (pH, ORP, and DO were used as real-time control parameters to adjust the duration of each operational phase in the IMT–A2O process. The control system is an algorithm that automatically adjusts the cycle length to the influent wastewater characteristics according to the end points. It was found that on-line sensor values of pH, ORP, and DO were somehow related with the dynamic behaviors of nutrient concentrations in IMT–A2O. The algorithm acts in the reaction phases of the IMT–A2O cycle using ORP and pH break points of tank one to distinguish the end of denitrification and the beginning of phosphorus release, pH break point of tank two to control the end of denitrification and beginning of phosphorus release and a sudden increase in DO pattern, pH break point and ORP to control phosphorus uptake and the end of the nitrification process. Although the fluctuations in raw wastewater concentration are extreme; an influent with a low C/N ratio is deficient in organic carbon, and a low carbon source level can limit the overall biological denitrification process, the average removal efficiencies achieved for COD, ammonia–nitrogen, total nitrogen and total phosphorus were not less than 76.11%, 87.78%, 76.45% and 83.75%, respectively, using the integrated real-time control strategy. The integrated IMT–A2O exhibited a better performance in nutrient removal than the

Bioenergy Sorghum Crop Model Predicts VPD-Limited Transpiration Traits Enhance Biomass Yield in Water-Limited Environments.

Science.gov (United States)

Truong, Sandra K; McCormick, Ryan F; Mullet, John E

2017-01-01

Bioenergy sorghum is targeted for production in water-limited annual cropland therefore traits that improve plant water capture, water use efficiency, and resilience to water deficit are necessary to maximize productivity. A crop modeling framework, APSIM, was adapted to predict the growth and biomass yield of energy sorghum and to identify potentially useful traits for crop improvement. APSIM simulations of energy sorghum development and biomass accumulation replicated results from field experiments across multiple years, patterns of rainfall, and irrigation schemes. Modeling showed that energy sorghum's long duration of vegetative growth increased water capture and biomass yield by ~30% compared to short season crops in a water-limited production region. Additionally, APSIM was extended to enable modeling of VPD-limited transpiration traits that reduce crop water use under high vapor pressure deficits (VPDs). The response of transpiration rate to increasing VPD was modeled as a linear response until a VPD threshold was reached, at which the slope of the response decreases, representing a range of responses to VPD observed in sorghum germplasm. Simulation results indicated that the VPD-limited transpiration trait is most beneficial in hot and dry regions of production where crops are exposed to extended periods without rainfall during the season or to a terminal drought. In these environments, slower but more efficient transpiration increases biomass yield and prevents or delays the exhaustion of soil water and onset of leaf senescence. The VPD-limited transpiration responses observed in sorghum germplasm increased biomass accumulation by 20% in years with lower summer rainfall, and the ability to drastically reduce transpiration under high VPD conditions could increase biomass by 6% on average across all years. This work indicates that the productivity and resilience of bioenergy sorghum grown in water-limited environments could be further enhanced by development

How phosphorus limitation can control climate-active gas sources and sinks

Science.gov (United States)

Gypens, Nathalie; Borges, Alberto V.; Ghyoot, Caroline

2017-06-01

Since the 1950's, anthropogenic activities have increased nutrient river loads to European coastal areas. Subsequent implementation of nutrient reduction policies have led to considerably reduction of phosphorus (P) loads from the mid-1980's, while nitrogen (N) loads were maintained, inducing a P limitation of phytoplankton growth in many eutrophied coastal areas such as the Southern Bight of the North Sea (SBNS). When dissolved inorganic phosphorus (DIP) is limiting, most phytoplankton organisms are able to indirectly acquire P from dissolved organic P (DOP). We investigate the impact of DOP use on phytoplankton production and atmospheric fluxes of CO2 and dimethylsulfide (DMS) in the SBNS from 1951 to 2007 using an extended version of the R-MIRO-BIOGAS model. This model includes a description of the ability of phytoplankton organisms to use DOP as a source of P. Results show that primary production can increase up to 30% due to DOP uptake under limiting DIP conditions. Consequently, simulated DMS emissions also increase proportionally while CO2 emissions to the atmosphere decrease, relative to the reference simulation without DOP uptake.

Environment control system

International Nuclear Information System (INIS)

Sammarone, D.G.

1978-01-01

Disclosed is a system for controlling the environment of an enclosed area in nuclear reactor installations. The system permits the changing of the environment from nitrogen to air, or from air to nitrogen, without the release of any radioactivity or process gas to the outside atmosphere

The Liquid Lithium Limiter control system on FTU

International Nuclear Information System (INIS)

Bertocchi, A.; Panella, M.; Vitale, V.; Sinibaldi, S.

2006-01-01

In the second half of 2005, a liquid lithium limiter (LLL) with capillary porous system configuration was installed for testing on the FTU tokamak. The liquid lithium flows through capillaries from a reservoir to the side facing the plasma to form a thin liquid lithium film. The system is composed of three stainless steel sections, which contain two thermocouples each. A heating system brings the Li temperature to about 200 o C allowing the liquid to flow. This temperature, monitored by thermocouples, needs to be controlled. [M. Apicella, G. Mazzitelli et al., First experiment with Lithium Limiter on FTU, 17 o International Conference on Plasma Surface Interaction in Controlled Fusion Devices, 22 - 26 May 2006, Hefei Anhui, China]. To carry out this experimental procedure, some new features have been introduced in the existent control system based on Opto22 TM modules and a CORBA/PHP/MySQL software architecture [A. Bertocchi, S. Podda, V. Vitale, Fusion Eng. Des. 74 (2005) 787-791]. The historical data storage to keep the lithium temperature evolution has been added. Two graphical tools - developed in MATLab and Java environments respectively to monitor the lithium temperature coming from thermocouples - have been also implemented. The control system allows regulating the heater temperature in each section of the LLL to reach operational conditions, where the temperature adjustment can be performed either automatically through a specific control law or manually by the operator. During plasma operations the system switches off the limiter power supply to prevent instruments damage. Moreover, in the same experimental context, a first approach to automatically obtain executable code - starting from control laws designed by Simulink TM tool - has been realized. (author)

Virtualization in control system environment

International Nuclear Information System (INIS)

Shen, L.R.; Liu, D.K.; Wan, T.M.

2012-01-01

In large scale distributed control system, there are lots of common service composed an environment for the entire control system, such as the server system for the common software base library, application server, archive server and so on. This paper gives a description of a virtualization realization for control system environment including the virtualization for server, storage, network system and application for the control system. With a virtualization instance of the EPICS based control system environment that was built by the VMware vSphere v4, we tested the whole functionality of this virtualization environment in the SSRF control system, including the common server of the NFS, NIS, NTP, Boot and EPICS base and extension library tools, we also have applied virtualization to application servers such as the Archive, Alarm, EPICS gateway and all of the network based IOC. Specially, we test the high availability and VMotion for EPICS asynchronous IOC successful under the different VLAN configuration of the current SSRF control system network. (authors)

Fluvial Export Variability Of Limiting Nutrient Fluxes To The Indian Ocean From Kelani, Kalu and Gin Rivers Of Sri Lanka

Science.gov (United States)

Ranasinghage, P. N.; Silva, A. N.; Vlahos, P.

2016-12-01

Inorganic `reactive' nutrients hold the highest importance in understanding the role of limiting nutrients in the ocean since they facilitate marine biological productivity and carbon sequestration that would eventually pave the way to regulate the biogeochemical climate feedbacks. Significant inorganic fractions are expected to be exported episodically to the ocean from fluvial fluxes though this is poorly understood. Thus, no considerable amounts of published work regarding the fluxes from Sri Lankan freshwater streams have ever been recorded. A study was carried out to quantify the contribution of Kelani, Kalu and Gin Rivers, three major rivers in the wet zone of Sri Lanka, in exporting major limiting nutrient fluxes to the Indian Ocean; to understand the significance of their variability patterns with rainfall and understand differences in their inputs. The study was conducted during the summer monsoonal period from late August to early November at two-three week intervals where water samples were collected for ammonia, nitrite, nitrate, orthophosphate, silica, sulfate and iron analysis by Colorimetric Spectroscopy. Discharge and rainfall data were retrieved from the Department of Irrigation and Department of Meteorology, Sri Lanka respectively. According to Two Way ANOVA, none of the individual fluxes showed significant differences (p>0.1) both in their temporal and spatial variability suggesting that studied rivers respond similarly in fluvial transportation owing to the similar rainfall intensities observed during the study period in the wet zone. Linear Regression Analysis indicates that only PO43- (p<0.01), SO42- (p<0.01) and NO2-(p<0.01 for Kelani and Kalu; 0.0.1Key words; nutrients, fluvial, fluxes, Redfield ratios

Characterization of nutrient deficiency in Hancornia speciosa Gomes seedlings by omitting micronutrients from the nutrient solution

Directory of Open Access Journals (Sweden)

Layara Alexandre Bessa

2013-06-01

Full Text Available Hancornia speciosa Gomes (Mangaba tree is a fruit tree belonging to the Apocynaceae family and is native to Brazil. The production of seedlings of this species is limited by a lack of technical and nutritional expertise. To address this deficiency, this study aimed to characterize the visual symptoms of micronutrient deficiency and to assess growth and leaf nutrient accumulation in H. speciosa seedlings supplied with nutrient solutions that lack individual micronutrients. H. speciosa plants were grown in nutrient solution in a greenhouse according to a randomized block design, with four replicates. The treatments consisted of a group receiving complete nutrient solution and groups treated with a nutrient solution lacking one of the following micronutrients: boron (B, copper (Cu, iron (Fe, manganese (Mn, zinc (Zn, and molybdenum (Mo. The visual symptoms of nutrient deficiency were generally easy to characterize. Dry matter production was affected by the omission of micronutrients, and the treatment lacking Fe most limited the stem length, stem diameter, root length, and number of leaves in H. speciosa seedlings as well as the dry weight of leaves, the total dry weight, and the relative growth in H. speciosa plants. The micronutrient contents of H. speciosa leaves from plants receiving the complete nutrient solution treatment were, in decreasing order, Fe>Mn>Cu>Zn>B.

Maternal–Fetal Nutrient Transport in Pregnancy Pathologies: The Role of the Placenta

Directory of Open Access Journals (Sweden)

Kendra Elizabeth Brett

2014-09-01

Full Text Available Appropriate in utero growth is essential for offspring development and is a critical contributor to long-term health. Fetal growth is largely dictated by the availability of nutrients in maternal circulation and the ability of these nutrients to be transported into fetal circulation via the placenta. Substrate flux across placental gradients is dependent on the accessibility and activity of nutrient-specific transporters. Changes in the expression and activity of these transporters is implicated in cases of restricted and excessive fetal growth, and may represent a control mechanism by which fetal growth rate attempts to match availability of nutrients in maternal circulation. This review provides an overview of placenta nutrient transport with an emphasis on macro-nutrient transporters. It highlights the changes in expression and activity of these transporters associated with common pregnancy pathologies, including intrauterine growth restriction, macrosomia, diabetes and obesity, as well as the potential impact of maternal diet. Molecular signaling pathways linking maternal nutrient availability and placenta nutrient transport are discussed. How sexual dimorphism affects fetal growth strategies and the placenta’s response to an altered intrauterine environment is considered. Further knowledge in this area may be the first step in the development of targeted interventions to help optimize fetal growth.

Nutrient controls on biocomplexity of mangrove ecosystems

Science.gov (United States)

McKee, Karen L.

2004-01-01

Mangrove forests are important coastal ecosystems that provide a variety of ecological and societal services. These intertidal, tree-dominated communities along tropical coastlines are often described as “simple systems,” compared to other tropical forests with larger numbers of plant species and multiple understory strata; however, mangrove ecosystems have complex trophic structures, and organisms exhibit unique physiological, morphological, and behavioral adaptations to environmental conditions characteristic of the land-sea interface. Biogeochemical functioning of mangrove forests is also controlled by interactions among the microbial, plant, and animal communities and feedback linkages mediated by hydrology and other forcing functions. Scientists with the U.S. Geological Survey (USGS) at the National Wetlands Research Center are working to understand more fully the impact of nutrient variability on these delicate and important ecosystems.

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.

The metabolic response of P. putida KT2442 producing high levels of polyhydroxyalkanoate under single- and multiple-nutrient-limited growth: Highlights from a multi-level omics approach

Directory of Open Access Journals (Sweden)

Poblete-Castro Ignacio

2012-03-01

Full Text Available Abstract Background Pseudomonas putida KT2442 is a natural producer of polyhydroxyalkanoates (PHAs, which can substitute petroleum-based non-renewable plastics and form the basis for the production of tailor-made biopolymers. However, despite the substantial body of work on PHA production by P. putida strains, it is not yet clear how the bacterium re-arranges its whole metabolism when it senses the limitation of nitrogen and the excess of fatty acids as carbon source, to result in a large accumulation of PHAs within the cell. In the present study we investigated the metabolic response of KT2442 using a systems biology approach to highlight the differences between single- and multiple-nutrient-limited growth in chemostat cultures. Results We found that 26, 62, and 81% of the cell dry weight consist of PHA under conditions of carbon, dual, and nitrogen limitation, respectively. Under nitrogen limitation a specific PHA production rate of 0.43 (g·(g·h-1 was obtained. The residual biomass was not constant for dual- and strict nitrogen-limiting growth, showing a different feature in comparison to other P. putida strains. Dual limitation resulted in patterns of gene expression, protein level, and metabolite concentrations that substantially differ from those observed under exclusive carbon or nitrogen limitation. The most pronounced differences were found in the energy metabolism, fatty acid metabolism, as well as stress proteins and enzymes belonging to the transport system. Conclusion This is the first study where the interrelationship between nutrient limitations and PHA synthesis has been investigated under well-controlled conditions using a system level approach. The knowledge generated will be of great assistance for the development of bioprocesses and further metabolic engineering work in this versatile organism to both enhance and diversify the industrial production of PHAs.

Mechanisms for success after long-term nutrient enrichment in a boreal forest understory.

Directory of Open Access Journals (Sweden)

Tess Nahanni Grainger

Full Text Available Global levels of reactive nitrogen are predicted to rise in the coming decades as a result of increased deposition from the burning of fossil fuels and the large-scale conversion of nitrogen into a useable form for agriculture. Many plant communities respond strongly to increases in soil nitrogen, particularly in northern ecosystems where nitrogen levels are naturally very low. An experiment in northern Canada that was initiated in 1990 has been investigating the effects of long-term nutrient enrichment (fertilizer added annually on a boreal forest understory community. We used this experiment to investigate why some species increase in abundance under nutrient enrichment whereas others decline. We focused on four species that differed in their responses to fertilization: Mertensia paniculata and Epilobium angustifolium increased in abundance, Achillea millefolium remained relatively constant and Festuca altaica declined. We hypothesized that the two species that were successful in the new high-nutrient, light-limited environment would be taller, have higher specific leaf area, change phenology by growing earlier in the season and be more morphologically plastic than their less successful counterparts. We compared plant height, specific leaf area, growth spurt date and allocation to leaves in plants grown in control and fertilized plots. We demonstrated that each of the two species that came to dominate fertilized plots has a different combination of traits and responses that likely gave them a competitive advantage; M. paniculata has the highest specific leaf area of the four species whereas E. angustifolium is tallest and exhibits morphological plasticity when fertilized by increasing biomass allocation to leaves. These results indicate that rather than one strategy determining success when nutrients become available, a variety of traits and responses may contribute to a species' ability to persist in a nutrient-enriched boreal forest

Nutrients and toxin producing phytoplankton control algal blooms ...

Indian Academy of Sciences (India)

Unknown

capacity for the phytoplankton population depends on the nutrient level. The role of nutrient ..... irregular oscillations with time, gives rise to rich class of models ..... the Indian river lagoon, Florida, USA; J. Plankton Res. 26. 1229– ... Sea Res. 18 82–96. Graneli E et al 1989 From anoxia to fish poisoning: The last ten years of ...

Emiliania huxleyi endures N-limitation with an efficient metabolic budgeting and effective ATP synthesis.

Science.gov (United States)

Rokitta, Sebastian D; Von Dassow, Peter; Rost, Björn; John, Uwe

2014-12-02

Global change will affect patterns of nutrient upwelling in marine environments, potentially becoming even stricter regulators of phytoplankton primary productivity. To better understand phytoplankton nutrient utilization on the subcellular basis, we assessed the transcriptomic responses of the life-cycle stages of the biogeochemically important microalgae Emiliania huxleyi to nitrogen-limitation. Cells grown in batch cultures were harvested at 'early' and 'full' nitrogen-limitation and were compared with non-limited cells. We applied microarray-based transcriptome profilings, covering ~10.000 known E. huxleyi gene models, and screened for expression patterns that indicate the subcellular responses. The diploid life-cycle stage scavenges nitrogen from external organic sources and -like diatoms- uses the ornithine-urea cycle to rapidly turn over cellular nitrogen. The haploid stage reacts similarly, although nitrogen scavenging is less pronounced and lipid oxidation is more prominent. Generally, polyamines and proline appear to constitute major organic pools that back up cellular nitrogen. Both stages induce a malate:quinone-oxidoreductase that efficiently feeds electrons into the respiratory chain and drives ATP generation with reduced respiratory carbon throughput. The use of the ornithine-urea cycle to budget the cellular nitrogen in situations of limitation resembles the responses observed earlier in diatoms. This suggests that underlying biochemical mechanisms are conserved among distant clades of marine phototrophic protists. The ornithine-urea cycle and proline oxidation appear to constitute a sensory-regulatory system that monitors and controls cellular nitrogen budgets under limitation. The similarity between the responses of the life-cycle stages, despite the usage of different genes, also indicates a strong functional consistency in the responses to nitrogen-limitation that appears to be owed to biochemical requirements. The malate

Nutrient sensing and signaling in the yeast Saccharomyces cerevisiae

Science.gov (United States)

Conrad, Michaela; Schothorst, Joep; Kankipati, Harish Nag; Van Zeebroeck, Griet; Rubio-Texeira, Marta; Thevelein, Johan M

2014-01-01

The yeast Saccharomyces cerevisiae has been a favorite organism for pioneering studies on nutrient-sensing and signaling mechanisms. Many specific nutrient responses have been elucidated in great detail. This has led to important new concepts and insight into nutrient-controlled cellular regulation. Major highlights include the central role of the Snf1 protein kinase in the glucose repression pathway, galactose induction, the discovery of a G-protein-coupled receptor system, and role of Ras in glucose-induced cAMP signaling, the role of the protein synthesis initiation machinery in general control of nitrogen metabolism, the cyclin-controlled protein kinase Pho85 in phosphate regulation, nitrogen catabolite repression and the nitrogen-sensing target of rapamycin pathway, and the discovery of transporter-like proteins acting as nutrient sensors. In addition, a number of cellular targets, like carbohydrate stores, stress tolerance, and ribosomal gene expression, are controlled by the presence of multiple nutrients. The protein kinase A signaling pathway plays a major role in this general nutrient response. It has led to the discovery of nutrient transceptors (transporter receptors) as nutrient sensors. Major shortcomings in our knowledge are the relationship between rapid and steady-state nutrient signaling, the role of metabolic intermediates in intracellular nutrient sensing, and the identity of the nutrient sensors controlling cellular growth. PMID:24483210

Nutrient-sensing nuclear receptors PPARα and FXR control liver energy balance.

Science.gov (United States)

Preidis, Geoffrey A; Kim, Kang Ho; Moore, David D

2017-04-03

The nuclear receptors PPARα (encoded by NR1C1) and farnesoid X receptor (FXR, encoded by NR1H4) are activated in the liver in the fasted and fed state, respectively. PPARα activation induces fatty acid oxidation, while FXR controls bile acid homeostasis, but both nuclear receptors also regulate numerous other metabolic pathways relevant to liver energy balance. Here we review evidence that they function coordinately to control key nutrient pathways, including fatty acid oxidation and gluconeogenesis in the fasted state and lipogenesis and glycolysis in the fed state. We have also recently reported that these receptors have mutually antagonistic impacts on autophagy, which is induced by PPARα but suppressed by FXR. Secretion of multiple blood proteins is a major drain on liver energy and nutrient resources, and we present preliminary evidence that the liver secretome may be directly suppressed by PPARα, but induced by FXR. Finally, previous studies demonstrated a striking deficiency in bile acid levels in malnourished mice that is consistent with results in malnourished children. We present evidence that hepatic targets of PPARα and FXR are dysregulated in chronic undernutrition. We conclude that PPARα and FXR function coordinately to integrate liver energy balance.

Study on shrimp waste water and vermicompost as a nutrient source for bell peppers

Science.gov (United States)

The aquaculture industry generates significant nutrient-rich wastewater that is released into streams and rivers causing environmental concern. The objective of this controlled environment study was to evaluate the effect of waste shrimp water (SW), vermicompost (VC), at rates of 10%, 20%, 40%, and ...

The Liquid Lithium Limiter control system on FTU

Energy Technology Data Exchange (ETDEWEB)

Bertocchi, A; Panella, M; Vitale, V [Associazione EURATOM- ENEA sulla Fusione, Via Enrico Fermi 45, I-00044 Frascati (RM) (Italy); Sinibaldi, S [Rome University ' ' Tor Vergata ' ' , Informatics, Systems and Production Dept., Via del Politecnico 1, 00133 Rome (Italy)

2006-07-01

In the second half of 2005, a liquid lithium limiter (LLL) with capillary porous system configuration was installed for testing on the FTU tokamak. The liquid lithium flows through capillaries from a reservoir to the side facing the plasma to form a thin liquid lithium film. The system is composed of three stainless steel sections, which contain two thermocouples each. A heating system brings the Li temperature to about 200 {sup o}C allowing the liquid to flow. This temperature, monitored by thermocouples, needs to be controlled. [M. Apicella, G. Mazzitelli et al., First experiment with Lithium Limiter on FTU, 17{sup o} International Conference on Plasma Surface Interaction in Controlled Fusion Devices, 22 - 26 May 2006, Hefei Anhui, China]. To carry out this experimental procedure, some new features have been introduced in the existent control system based on Opto22{sup TM} modules and a CORBA/PHP/MySQL software architecture [A. Bertocchi, S. Podda, V. Vitale, Fusion Eng. Des. 74 (2005) 787-791]. The historical data storage to keep the lithium temperature evolution has been added. Two graphical tools - developed in MATLab and Java environments respectively to monitor the lithium temperature coming from thermocouples - have been also implemented. The control system allows regulating the heater temperature in each section of the LLL to reach operational conditions, where the temperature adjustment can be performed either automatically through a specific control law or manually by the operator. During plasma operations the system switches off the limiter power supply to prevent instruments damage. Moreover, in the same experimental context, a first approach to automatically obtain executable code - starting from control laws designed by Simulink{sup TM} tool - has been realized. (author)

Nutrients and Other Environmental Factors Influence Virus Abundances across Oxic and Hypoxic Marine Environments

Directory of Open Access Journals (Sweden)

Jan F. Finke

2017-06-01

Full Text Available Virus particles are highly abundant in seawater and, on average, outnumber microbial cells approximately 10-fold at the surface and 16-fold in deeper waters; yet, this relationship varies across environments. Here, we examine the influence of a suite of environmental variables, including nutrient concentrations, salinity and temperature, on the relationship between the abundances of viruses and prokaryotes over a broad range of spatial and temporal scales, including along a track from the Northwest Atlantic to the Northeast Pacific via the Arctic Ocean, and in the coastal waters of British Columbia, Canada. Models of varying complexity were tested and compared for best fit with the Akaike Information Criterion, and revealed that nitrogen and phosphorus concentrations, as well as prokaryote abundances, either individually or combined, had significant effects on viral abundances in all but hypoxic environments, which were only explained by a combination of physical and chemical factors. Nonetheless, multivariate models of environmental variables showed high explanatory power, matching or surpassing that of prokaryote abundance alone. Incorporating both environmental variables and prokaryote abundances into multivariate models significantly improved the explanatory power of the models, except in hypoxic environments. These findings demonstrate that environmental factors could be as important as, or even more important than, prokaryote abundance in describing viral abundance across wide-ranging marine environments

Nutrient control for stationary phase cellulase production in Trichoderma reesei Rut C-30.

Science.gov (United States)

Callow, Nicholas V; Ray, Christopher S; Kelbly, Matthew A; Ju, Lu-Kwang

2016-01-01

This work describes the use of nutrient limitations with Trichoderma reesei Rut C-30 to obtain a prolonged stationary phase cellulase production. This period of non-growth may allow for dependable cellulase production, extended fermentation periods, and the possibility to use pellet morphology for easy product separation. Phosphorus limitation was successful in halting growth and had a corresponding specific cellulase production of 5±2 FPU/g-h. Combined with the addition of Triton X-100 for fungal pellet formation and low shear conditions, a stationary phase cellulase production period in excess of 300 h was achieved, with a constant enzyme production rate of 7±1 FPU/g-h. While nitrogen limitation was also effective as a growth limiter, it, however, also prevented cellulase production. Copyright © 2015 Elsevier Inc. All rights reserved.

Roots bridge water to nutrients: a study of utilizing hydraulic redistribution through root systems to extract nutrients in the dry soils

Science.gov (United States)

Yan, J.; Ghezzehei, T. A.

2017-12-01

The rhizosphere is the region of soil that surrounds by individual plant roots. While its small volume and narrow region compared to bulk soil, the rhizosphere regulates numerous processes that determine physical structure, nutrient distribution, and biodiversity of soils. One of the most important and distinct functions of the rhizosphere is the capacity of roots to bridge and redistribute soil water from wet soil layers to drier layers. This process was identified and defined as hydraulic lift or hydraulic redistribution, a passive process driven by gradients in water potentials and it has attracted much research attention due to its important role in global water circulation and agriculture security. However, while previous studies mostly focused on the hydrological or physiological impacts of hydraulic redistribution, limited research has been conducted to elucidate its role in nutrient cycling and uptake. In this study, we aim to test the possibility of utilizing hydraulic redistribution to facilitate the nutrient movement and uptake from resource segregated zone. Our overarching hypothesis is that plants can extract nutrients from the drier but nutrient-rich regions by supplying sufficient amounts of water from the wet but nutrient-deficient regions. To test our hypothesis, we designed split-root systems of tomatoes with unequal supply of water and nutrients in different root compartments. More specifically, we transplanted tomato seedlings into sand or soil mediums, and grew them under conditions with alternate 12-h lightness and darkness. We continuously monitored the temperature, water and nutrient content of soils in these separated compartments. The above and below ground biomass were also quantified to evaluate the impacts on the plant growth. The results were compared to a control with evenly supply of water and nutrients to assess the plant growth, nutrient leaching and uptake without hydraulic redistribution.

Mussels as a tool for mitigation of nutrients in the marine environment

DEFF Research Database (Denmark)

Petersen, Jens Kjerulf; Hasler, Berit; Timmermann, Karen

2014-01-01

Long-line mussel farming has been proposed as a mitigation tool for removal of excess nutrients in eutrophic coastal waters. A full-scale mussel farm optimized for cost efficient nutrient removal was established in the eutrophic Skive Fjord, Denmark where biological and economic parameters related...... to establishment, maintenance and harvest revealed that mussel production optimized for mitigation can be carried out at a lower cost compared to mussel production for (human) consumption. The costs for nutrient removal was 14.8€kg−1N making mitigation mussel production a cost-efficient measure compared...

Light-limited growth and competition for light in well-mixed aquatic environments : An elementary model

NARCIS (Netherlands)

Huisman, Jef; Weissing, F.J.

Light is never distributed homogeneously since it forms a gradient over biomass. As a consequence, the common theories on nutrient competition are not applicable to competition for light. In this paper, we investigate a model for light-limited growth and competition among phytoplankton species in a

On the Radiation Protection of the Environment

International Nuclear Information System (INIS)

Soberhart, L. J.; Clausse, A.; D'Amato, E.

2004-01-01

Over the last decade, substantial advances in what is know as legal protection of the environment, -as a different matter from human being protection- have been made. Some national legislations include serious penalties against environmental damage. It is becoming customary to consider a serious offence any excess in the prescribed limits of radioactive materials release to the environment. What these limits mean, however, is not completely clear nowadays. According to the International Commission on Radiological Protection (ICRP) the standards of environmental control needed to protect man to the degree currently thought desirable will ensure that other species are not put at risk, although, occasionally, individual members of non human species might be harmed. However the use of limits of radioactive releases resulting from the direct application of ICRP recommend limits as legal references for the applicable offences in environmental protection is certainly a misconception. In this paper a conceptual framework for the calculation of legal limits for environmental radioprotection are presented. The approach is based on an ecosystem perspective, assessing the impact of radioactive releases on the ecosystem dynamics and equilibrium. The method is based on functional groups models -i.e. groups of species that are selected from a number of criteria such as play similar rules in the chain of nutrients or have the same radiosensitivity- providing the basis for prescribed limits of the radioactive material release to the environment. The methodology is applied to a system of three functional groups in equilibrium, with is affected by radioactive intrusion. Different impacts on the equilibrium can be identified, depending on the amount of radioactive material released to the environment. It is shown how the concept of equilibrium breakdown can be applied in order to assess the radiological impact. (Author) 8 refs

N-limited or N and P co-limited indications in the surface waters of three Mediterranean basins

Science.gov (United States)

Tanaka, T.; Thingstad, T. F.; Christaki, U.; Colombet, J.; Cornet-Barthaux, V.; Courties, C.; Grattepanche, J.-D.; Lagaria, A.; Nedoma, J.; Oriol, L.; Psarra, S.; Pujo-Pay, M.; van Wambeke, F.

2010-11-01

The limiting nutrient for the pelagic microbial food web in the Mediterranean Sea was investigated in the nutrient manipulated microcosms during summer 2008. Surface waters were collected into 12 carboys at a center of anticyclonic eddy at the Western Basin, the Ionian Basin, and the Levantine Basin, respectively. As compared to the Redfield ratio, the ratio of N to P in the collected waters was always smaller in the dissolved inorganic fraction but higher in both dissolved and particulate organic fractions. Four different treatments in triplicates (addition of ammonium, phosphate, a combination of both, and the unamended control) were set up for the carboys. Responses of chemical and biological parameters in these different treatments were measured during the incubation (3-4 days). Temporal changes of turnover time of phosphate and ATP, and alkaline phosphatase activity during the incubation suggested that the phytoplankton and heterotrophic prokaryotes (Hprok) communities were not purely P-limited at any studied stations. Statistical comparison between the treatments for a given parameter measured at the end of the incubation did not find pure P-limitation in any chemical and biological parameters at three study sites. Primary production was consistently limited by N, and Hprok growth was not limited by N nor P in the Western Basin, but N-limited in the Ionian Basin, and N and P co-limited in the Levantine Basin. Our results demonstrated the gap between biogeochemical features and biological responses in terms of the limiting nutrient. We question the general notion that Mediterranean surface waters are limited by P alone during the stratified period.

Potential for nutrient recovery and biogas production from blackwater, food waste and greywater in urban source control systems.

Science.gov (United States)

Kjerstadius, H; Haghighatafshar, S; Davidsson, Å

2015-01-01

In the last decades, the focus on waste and wastewater treatment systems has shifted towards increased recovery of energy and nutrients. Separation of urban food waste (FW) and domestic wastewaters using source control systems could aid this increase; however, their effect on overall sustainability is unknown. To obtain indicators for sustainability assessments, five urban systems for collection, transport, treatment and nutrient recovery from blackwater, greywater and FW were investigated using data from implementations in Sweden or northern Europe. The systems were evaluated against their potential for biogas production and nutrient recovery by the use of mass balances for organic material, nutrients and metals over the system components. The resulting indicators are presented in units suitable for use in future sustainability studies or life-cycle assessment of urban waste and wastewater systems. The indicators show that source control systems have the potential to increase biogas production by more than 70% compared with a conventional system and give a high recovery of phosphorus and nitrogen as biofertilizer. The total potential increase in gross energy equivalence for source control systems was 20-100%; the greatest increase shown is for vacuum-based systems.

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.

Demographic parameters of individual E.coli within and among controlled environment

DEFF Research Database (Denmark)

Jouvet, Lionel; Steiner, Ulrich

2014-01-01

. This can be achieved by working on isogenic populations under controlled environments. We use a microfluidic device to limit stochastic processes to their molecular components. The high throughput microfluidic device traps thousands of individual E. coli cells and tracks them over their lifespan...

Security in Distributed Collaborative Environments: Limitations and Solutions

Science.gov (United States)

Saadi, Rachid; Pierson, Jean-Marc; Brunie, Lionel

The main goal of establishing collaboration between heterogeneous environment is to create such as Pervasive context which provide nomadic users with ubiquitous access to digital information and surrounding resources. However, the constraints of mobility and heterogeneity arise a number of crucial issues related to security, especially authentication access control and privacy. First of all, in this chapter we explore the trust paradigm, specially the transitive capability to enable a trust peer to peer collaboration. In this manner, when each organization sets its own security policy to recognize (authenticate) users members of a trusted community and provide them a local access (access control), the trust transitivity between peers will allows users to gain a broad, larger and controlled access inside the pervasive environment. Next, we study the problem of user's privacy. In fact in pervasive and ubiquitous environments, nomadic users gather and exchange certificates or credential which providing them rights to access by transitivity unknown and trusted environments. These signed documents embeds increasing number of attribute that require to be filtered according to such contextual situation. In this chapter, we propose a new morph signature enabling each certificate owner to preserve his privacy by discloses or blinds some sensitive attributes according to faced situation.

Controls of event-based nutrient transport within nested headwater agricultural watersheds of the western Lake Erie basin

Science.gov (United States)

Williams, Mark R.; Livingston, Stanley J.; Penn, Chad J.; Smith, Douglas R.; King, Kevin W.; Huang, Chi-hua

2018-04-01

Understanding the processes controlling nutrient delivery in headwater agricultural watersheds is essential for predicting and mitigating eutrophication and harmful algal blooms in receiving surface waters. The objective of this study was to elucidate nutrient transport pathways and examine key components driving nutrient delivery processes during storm events in four nested agricultural watersheds (298-19,341 ha) in the western Lake Erie basin with poorly drained soils and an extensive artificial drainage network typical of the Midwestern U.S. Concentration-discharge hysteresis patterns of nitrate-nitrogen (NO3-N), dissolved reactive phosphorus (DRP), and particulate phosphorus (PP) occurring during 47 storm events over a 6 year period (2004-2009) were evaluated. An assessment of the factors producing nutrient hysteresis was completed following a factor analysis on a suite of measured environmental variables representing the fluvial and wider watershed conditions prior to, and during the monitored storm events. Results showed the artificial drainage network (i.e., surface tile inlets and subsurface tile drains) in these watersheds was the primary flow pathway for nutrient delivery to streams, but nutrient behavior and export during storm events was regulated by the flow paths to and the intensity of the drainage network, the availability of nutrients, and the relative contributions of upland and in-stream nutrient sources. Potential sources and flow pathways for transport varied among NO3-N, PP, and DRP with results underscoring the challenge of mitigating nutrient loss in these watersheds. Conservation practices addressing both nutrient management and hydrologic connectivity will likely be required to decrease nutrient loss in artificially drained landscapes.

The liquid lithium limiter control system on FTU

Energy Technology Data Exchange (ETDEWEB)

Bertocchi, A. [EURATOM-ENEA Association, Frascati Research Center, Via E. Fermi 45, 00044 Frascati (Rome) (Italy)], E-mail: bertocchi@frascati.enea.it; Di Donna, M [Department of Informatics, Systems and Productions, University of Rome Tor Vergata, Rome (Italy); Panella, M; Vitale, V [EURATOM-ENEA Association, Frascati Research Center, Via E. Fermi 45, 00044 Frascati (Rome) (Italy)

2007-10-15

In the second half of 2005, a liquid lithium limiter (LLL) with capillary porous system (CPS) configuration was installed to test on Tokamak FTU. The liquid lithium flows through capillaries from a reservoir to the side faced to the plasma to form a thin lithium film as wall coating. The system includes three stainless steel cases, which contain two thermocouples each one. A heating system brings the Li temperature about 200 deg. C to allow the liquid to flow. This temperature, monitored by thermocouples, needs to be controlled. To carry out this experimental procedure, some new features have been introduced in the existent control system based on Opto22{sup TM} modules and a CORBA/PHP/MySQL software architecture. The historical data storage to keep the lithium temperature evolution has been added. Two graphical tools - developed in MATLAB{sup TM} and Java environments, respectively, to monitor the lithium temperature coming from thermocouples - have been also implemented. The LLL control system allows to regulate the heater temperature in each unit to reach operational conditions, where the temperature adjustment can be performed either automatically through a specific control law or manually by the operator. During the plasma shot the system switches off the limiter power supply to prevent instruments damage. Moreover, in the same experimental context, a first approach to automatically obtain executable code - starting from control laws designed by Simulink{sup TM} tool - has been realized.

The liquid lithium limiter control system on FTU

International Nuclear Information System (INIS)

Bertocchi, A.; Di Donna, M.; Panella, M.; Vitale, V.

2007-01-01

In the second half of 2005, a liquid lithium limiter (LLL) with capillary porous system (CPS) configuration was installed to test on Tokamak FTU. The liquid lithium flows through capillaries from a reservoir to the side faced to the plasma to form a thin lithium film as wall coating. The system includes three stainless steel cases, which contain two thermocouples each one. A heating system brings the Li temperature about 200 deg. C to allow the liquid to flow. This temperature, monitored by thermocouples, needs to be controlled. To carry out this experimental procedure, some new features have been introduced in the existent control system based on Opto22 TM modules and a CORBA/PHP/MySQL software architecture. The historical data storage to keep the lithium temperature evolution has been added. Two graphical tools - developed in MATLAB TM and Java environments, respectively, to monitor the lithium temperature coming from thermocouples - have been also implemented. The LLL control system allows to regulate the heater temperature in each unit to reach operational conditions, where the temperature adjustment can be performed either automatically through a specific control law or manually by the operator. During the plasma shot the system switches off the limiter power supply to prevent instruments damage. Moreover, in the same experimental context, a first approach to automatically obtain executable code - starting from control laws designed by Simulink TM tool - has been realized

Microbiological treatment for removal of heavy metals and nutrients in FGD wastewater

Energy Technology Data Exchange (ETDEWEB)

Shulder, Stephen J. [Structural Integrity Associates, Annapolis, MD (United States); Riffe, Michael R. [Siemens Water Technologies, General Industry Solutions, Warrendale, PA (United States); Walp, Richard J. [URS Corporation, Princeton, NJ (United States)

2010-12-15

In efforts to comply with the Clean Air Act many coal-fired fossil plants are installing wet flue gas desulfurization (WFGD) systems, also known as scrubbers, to remove sulfur dioxide (SO{sub 2}). Limestone slurry is injected into an absorber to promote the formation of calcium sulfate (CaSO{sub 4}) or gypsum. Chloride (chlorine in the fuel) becomes dissolved and increases in the absorber loop, which can lead to a more corrosive environment. Inert matter in the limestone also enters the absorber and must be reduced to meet the gypsum quality specification. To control the buildup of chloride and fines in the flue gas desulfurization (FGD) system a continuous blowdown or purge stream is utilized. Environmental regulations on the discharge of treated FGD wastewater are becoming increasingly more stringent to control impacts on the receiving body of water (stream, lake, river, or ocean). These new limitations often focus on heavy metals such as selenium and nutrients including nitrogen and phosphorus compounds. The FGD chloride purge stream is typically treated by chemical addition and clarification to remove excess calcium and heavy metals with pH adjustment prior to discharge. However this process is not efficient at selenium or nutrient removal. Information on a new approach using biological reactor systems or sequencing batch reactors (SBRs) to achieve reductions in selenium and nitrogen compounds (ammonia, nitrite, and nitrate) is discussed. A brief discussion on the physical/chemical pretreatment is also provided. (orig.)

How phosphorus limitation can control climatic gas sources and sinks

Science.gov (United States)

Gypens, Nathalie; Borges, Alberto V.; Ghyoot, Caroline

2017-04-01

Since the 1950's, anthropogenic activities severely increased river nutrient loads in European coastal areas. Subsequent implementation of nutrient reduction policies have considerably reduced phosphorus (P) loads from mid-1980's, while nitrogen (N) loads were maintained, inducing a P limitation of phytoplankton growth in many eutrophied coastal areas such as the Southern Bight of the North Sea (SBNS). When dissolved inorganic phosphorous (DIP) is limiting, most phytoplankton organisms are able to indirectly acquire P from dissolved organic P (DOP). We investigate the impact of DOP use on the importance of phytoplankton production and atmospheric fluxes of CO2 and dimethylsulfide (DMS) in the SBNS from 1951 to 2007 using an extended version of the R-MIRO-BIOGAS model. This model includes a description of the ability of phytoplankton organisms to use DOP as a source of P. Results show that primary production can increase up to 70% due to DOP uptake in limiting DIP conditions. Consequently, simulated DMS emissions double while CO2 emissions to the atmosphere decrease, relative to the reference simulation without DOP uptake. At the end of the simulated period (late 2000's), the net direction of air-sea CO2 annual flux, changed from a source to a sink for atmospheric CO2 in response to use of DOP and increase of primary production.

Suppressed translation as a mechanism of initiation of CASP8 (caspase 8)-dependent apoptosis in autophagy-deficient NSCLC cells under nutrient limitation.

Science.gov (United States)

Allavena, Giulia; Cuomo, Francesca; Baumgartner, Georg; Bele, Tadeja; Sellgren, Alexander Yarar; Oo, Kyaw Soe; Johnson, Kaylee; Gogvadze, Vladimir; Zhivotovsky, Boris; Kaminskyy, Vitaliy O

2018-01-01

Macroautophagy/autophagy inhibition under stress conditions is often associated with increased cell death. We found that under nutrient limitation, activation of CASP8/caspase-8 was significantly increased in autophagy-deficient lung cancer cells, which precedes mitochondria outer membrane permeabilization (MOMP), CYCS/cytochrome c release, and activation of CASP9/caspase-9, indicating that under such conditions the activation of CASP8 is a primary event in the initiation of apoptosis as well as essential to reduce clonogenic survival of autophagy-deficient cells. Starvation leads to suppression of CFLAR proteosynthesis and accumulation of CASP8 in SQSTM1 puncta. Overexpression of CFLARs reduces CASP8 activation and apoptosis during starvation, while its silencing promotes efficient activation of CASP8 and apoptosis in autophagy-deficient U1810 lung cancer cells even under nutrient-rich conditions. Similar to starvation, inhibition of protein translation leads to efficient activation of CASP8 and cell death in autophagy-deficient lung cancer cells. Thus, here for the first time we report that suppressed translation leads to activation of CASP8-dependent apoptosis in autophagy-deficient NSCLC cells under conditions of nutrient limitation. Our data suggest that targeting translational machinery can be beneficial for elimination of autophagy-deficient cells via the CASP8-dependent apoptotic pathway.

Nutrient uptake dynamics across a gradient of nutrient concentrations and ratios at the landscape scale

Science.gov (United States)

Gibson, Catherine A.; O'Reilly, Catherine M.; Conine, Andrea L.; Lipshutz, Sondra M.

2015-02-01

Understanding interactions between nutrient cycles is essential for recognizing and remediating human impacts on water quality, yet multielemental approaches to studying nutrient cycling in streams are currently rare. Here we utilized a relatively new approach (tracer additions for spiraling curve characterization) to examine uptake dynamics for three essential nutrients across a landscape that varied in absolute and relative nutrient availability. We measured nutrient uptake for soluble reactive phosphorous, ammonium-nitrogen, and nitrate-nitrogen in 16 headwater streams in the Catskill Mountains, New York. Across the landscape, ammonium-nitrogen and soluble reactive phosphorus had shorter uptake lengths and higher uptake velocities than nitrate-nitrogen. Ammonium-nitrogen and soluble reactive phosphorus uptake velocities were tightly correlated, and the slope of the relationship did not differ from one, suggesting strong demand for both nutrients despite the high ambient water column dissolved inorganic nitrogen: soluble reactive phosphorus ratios. Ammonium-nitrogen appeared to be the preferred form of nitrogen despite much higher nitrate-nitrogen concentrations. The uptake rate of nitrate-nitrogen was positively correlated with ambient soluble reactive phosphorus concentration and soluble reactive phosphorus areal uptake rate, suggesting that higher soluble reactive phosphorus concentrations alleviate phosphorus limitation and facilitate nitrate-nitrogen uptake. In addition, these streams retained a large proportion of soluble reactive phosphorus, ammonium-nitrogen, and nitrate-nitrogen supplied by the watershed, demonstrating that these streams are important landscape filters for nutrients. Together, these results (1) indicated phosphorus limitation across the landscape but similarly high demand for ammonium-nitrogen and (2) suggested that nitrate-nitrogen uptake was influenced by variability in soluble reactive phosphorus availability and preference for

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.

Nutrient fluxes at the landscape level and the R* rule

Science.gov (United States)

Ju, Shu; DeAngelis, Donald L.

2010-01-01

Nutrient cycling in terrestrial ecosystems involves not only the vertical recycling of nutrients at specific locations in space, but also biologically driven horizontal fluxes between different areas of the landscape. This latter process can result in net accumulation of nutrients in some places and net losses in others. We examined the effects of such nutrient-concentrating fluxes on the R* rule, which predicts that the species that can survive in steady state at the lowest level of limiting resource, R*, can exclude all competing species. To study the R* rule in this context, we used a literature model of plant growth and nutrient cycling in which both nutrients and light may limit growth, with plants allocating carbon and nutrients between foliage and roots according to different strategies. We incorporated the assumption that biological processes may concentrate nutrients in some parts of the landscape. We assumed further that these processes draw nutrients from outside the zone of local recycling at a rate proportional to the local biomass density. Analysis showed that at sites where there is a sufficient biomass-dependent accumulation of nutrients, the plant species with the highest biomass production rates (roughly corresponding to the best competitors) do not reduce locally available nutrients to a minimum concentration level (that is, minimum R*), as expected from the R* rule, but instead maximize local nutrient concentration. These new results require broadening of our understanding of the relationships between nutrients and vegetation competition on the landscape level. The R* rule is replaced by a more complex criterion that varies across a landscape and reduces to the R* rule only under certain limiting conditions.

Diagnosis & Correction of Soil Nutrient Limitations in Intensively managed southern pine forests

Energy Technology Data Exchange (ETDEWEB)

University of Florida

2002-10-25

Forest productivity is one manner to sequester carbon and it is a renewable energy source. Likewise, efficient use of fertilization can be a significant energy savings. To date, site-specific use of fertilization for the purpose of maximizing forest productivity has not been well developed. Site evaluation of nutrient deficiencies is primarily based on empirical approaches to soil testing and plot fertilizer tests with little consideration for soil water regimes and contributing site factors. This project uses mass flow diffusion theory in a modeling context, combined with process level knowledge of soil chemistry, to evaluate nutrient bioavailability to fast-growing juvenile forest stands growing on coastal plain Spodosols of the southeastern U.S. The model is not soil or site specific and should be useful for a wide range of soil management/nutrient management conditions. In order to use the model, field data of fast-growing southern pine needed to be measured and used in the validation of the model. The field aspect of the study was mainly to provide data that could be used to verify the model. However, we learned much about the growth and development of fast growing loblolly. Carbon allocation patterns, root shoot relationships and leaf area root relationships proved to be new, important information. The Project Objectives were to: (1) Develop a mechanistic nutrient management model based on the COMP8 uptake model. (2) Collect field data that could be used to verify and test the model. (3) Model testing.

ACANTHAMOEBA SP.S-11 PHAGOCYTOTIC ACTIVITY ON MYCOBACTERIUM LEPRAE IN DIFFERENT NUTRIENT CONDITIONS.

Science.gov (United States)

Paling, Sepling; Wahyuni, Ratna; Ni'matuzahroh; Winarni, Dwi; Iswahyudi; Astari, Linda; Adriaty, Dinar; Agusni, Indropo; Izumi, Shinzo

2018-01-01

Mycobacterium leprae ( M. leprae ) is a pathogenic bacterium that causes leprosy. The presence of M. leprae in the environment is supported by microorganisms that act as the new host for M. leprae . Acanthamoeba 's potential to be a host of M. leprae in the environment. Acanthamoeba sp. is Free Living Amoeba (FLA) that classified as holozoic, saprophytic, and saprozoic. The existence of nutrients in the environment influence Acanthamoeba ability to phagocytosis or pinocytosis. This study is aimed to determine Acanthamoeba sp.S-11 phagocytic activity to Mycobacterium leprae ( M. leprae ) which cultured in non-nutrient media and riched-nutrient media. This research conducted by culturing Acanthamoeba sp.S-11 and M. leprae on different nutrient media conditions. M. leprae intracellular DNA were isolated and amplified by M. leprae specific primers through Real Time PCR (Q-PCR). The results showed that Acanthamoeba co-cultured on non-nutrient media were more active to phagocyte M. leprae than on rich-nutrient media. The use of non-nutrient media is recommended to optimize Acanthamoeba sp. phagocytic activity to M. leprae .

Strategic nutrient management of field pea in southwestern Uganda ...

African Journals Online (AJOL)

Strategic nutrient management of field pea in southwestern Uganda. ... African Journal of Food, Agriculture, Nutrition and Development ... Strategic nutrient management requires that the most limiting nutrient is known in order to provide a foundation for designing effective and sustainable soil fertility management ...

40 CFR 412.44 - Effluent limitations attainable by the application of the best conventional pollutant control...

Science.gov (United States)

2010-07-01

... application of the best conventional pollutant control technology (BCT). 412.44 Section 412.44 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS CONCENTRATED ANIMAL... limitations attainable by the application of the best conventional pollutant control technology (BCT). Except...

40 CFR 412.32 - Effluent limitations attainable by the application of the best conventional pollutant control...

Science.gov (United States)

2010-07-01

... application of the best conventional pollutant control technology (BCT). 412.32 Section 412.32 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS CONCENTRATED ANIMAL... Effluent limitations attainable by the application of the best conventional pollutant control technology...

Effluent release limits, sources and control

International Nuclear Information System (INIS)

Swindell, G.E.

1977-01-01

Objectives of radiation protection in relation to releases. Environmental transfer models for radionuclides. Relationship between releases, environmental levels and doses to persons. Establishment of release limits: Limits based on critical population group concept critical pathway analysis and identification of critical group. Limits based on optimization of radiation protection individual dose limits, collective doses and dose commitments 1) differential cost benefit analysis 2) authorized and operational limits taking account of future exposures. Monitoring of releases to the environment: Objectives of effluent monitoring. Typical sources and composition of effluents; design and operation of monitoring programmes; recording and reporting of monitoring results; complementary environmental monitoring. (orig.) [de

Predation and selection for antibiotic resistance in natural environments

DEFF Research Database (Denmark)

Leisner, Jørgen; Jørgensen, Niels O. G.; Middelboe, Mathias

2016-01-01

Genes encoding resistance to antibiotics appear, like the antibiotics themselves, to be ancient, originating long before the rise of the era of anthropogenic antibiotics. However, detailed understanding of the specific biological advantages of antibiotic resistance in natural environments is still...... lacking, thus limiting our efforts to prevent environmental influx of resistance genes. Here, we propose that antibiotic-resistant cells not only evade predation from antibiotic producers but also take advantage of nutrients released from cells that are killed by the antibiotic-producing bacteria. Thus......, predation is potentially an important mechanism for driving antibiotic resistance during slow or stationary phase of growth when nutrients are deprived. This adds to explain the ancient nature and widespread occurrence of antibiotic resistance in natural environments unaffected by anthropogenic antibiotics...

Nutrient intake during peritoneal dialysis at the Prince of Wales Hospital in Hong Kong.

Science.gov (United States)

Wang, Angela Yee-Moon; Sea, Mandy Man-Mei; Ng, Kenway; Kwan, Mandy; Lui, Siu-Fai; Woo, Jean

2007-05-01

Individuals undergoing peritoneal dialysis are at increased risk of developing cardiac disease and malnutrition. A cross-sectional survey. 249 Chinese continuous ambulatory peritoneal dialysis (CAPD) patients were recruited from the Prince of Wales Hospital in Hong Kong. Another 249 age- and sex-matched controls were recruited from an archive of 1,010 individuals with known food frequency questionnaire (FFQ) data. To compare the dietary intake pattern of CAPD patients with controls and evaluate its association with background cardiac disease. Intake of different nutrients was estimated by using a 7-day FFQ. Intake of all nutrients was lower in CAPD patients than controls, with resulting lower overall energy intake. Nutrient intake was decreased further in CAPD patients with background cardiac disease, which corresponded to worse nutritional status. Controlling for age, male sex, body weight, diabetes mellitus, dialysis therapy duration, residual renal function, peritoneal dialysis urea clearance, and Charlson Comorbidity Index score, background cardiac disease was associated independently with less intake of energy and most macronutrients and micronutrients. However, the association between background cardiac disease and energy and most nutrient intake was decreased or even lost when additional adjustment was made for C-reactive protein and serum albumin levels. An FFQ is limited in that nutrient quantitation is not exact and may be underestimated as a result of underreporting by patients. CAPD patients were compared with a control group without cardiovascular disease ascertainment that did not include subjects with diabetes. Chinese CAPD patients had significantly lower nutrient intake than age- and sex-matched controls. The association between cardiac disease and lower dietary macronutrient and micronutrient intake in CAPD patients was mediated in part through systemic inflammation, which also was associated with more malnutrition. More attention should be

CONTROL ENVIRONMENT IN KOSOVO PUBLIC INSTITUTIONS

Directory of Open Access Journals (Sweden)

Shaqir M. REXHEPI

2015-06-01

Full Text Available The study on how is Internal Control System developed in public institutions is of a special importance for modalities, forms and the manner of the application of relevant strategies for the functioning of internal control environment in public institutions. In this paper, there is treated the existing situation of internal control system environment of public finances and its implementation in public sector. For internal control system environment in public finances to function effectively, there should exist a coherent control environment which includes responsibilities for financial management from managers of Publicly Owned Enterprises and with complete functioning of internal audit, which exists in the function of development to add value. In Kosovo public institutions, this framework is offered by legislation and by institutional mechanism for the implementation of legislation according to these parameters.

EDUCATION IN GLOBAL INFORMATION-COMMUNICATION AND ANTHROPOGENIC ENVIRONMENT: NEW OPPORTUNITIES AND LIMITS

Directory of Open Access Journals (Sweden)

Sergey F. Sergeev

2013-01-01

Full Text Available The article answers the question of how to use global anthropogenic environments in order to create effective educational environment. We demonstrate both technological and didactic abilities and limits of modern environment-based technologies, and provide a new approach to the educational environment creation. 

Pharmaceutical consumption and residuals potentially relevant to nutrient cycling in Greater Accra, Ghana

Directory of Open Access Journals (Sweden)

Evren Sinar

2010-04-01

Full Text Available Recycling nutrients form sanitary wastes back into agricultural ecosystems offers an option to alleviate soil depletion in regions where the use of mineral fertiliser is limited. Exemplary nutrient and water cycling approaches, including collection, treatment and use of human urine, are established at Valley View University (VVU in Greater Accra, Ghana.Concerns have been recently raised in regard to fate and impact of pharmaceutical residues in soils and interlinked environment. To evaluate in how far emerging knowledge can be transposed onto VVU, urban and rural environments in Greater Accra, spatial disease occurrence and drug consumption patterns were studied. Malaria has been found to represent the most severe health burden in Ghana, but there is also a high prevalence of infectious diseases. Drugs consumed in great quantities and in respect to their residual loads potentially problematic in the environment belong to therapeutic groups of: antibiotics, analgesics, drugs for diabetes, antimalarials, cardiovascular drugs and anthelmintics. Drug consumption revealed to be highest in urban and lowest in rural areas. At VVU the range of consumed drugs is comparable to urban areas except for the negligible use of diabetes and cardiovascular medication as well as contraceptives.

Control of the radiation environment and the worker in high-energy facilities

International Nuclear Information System (INIS)

Stevenson, G.R.

1993-01-01

The philosophy behind the prediction, measurement, monitoring and limitation by access control of the radiation hazard in high-energy accelerator facilities is compared with that which could be employed for controlling similar hazards due to cosmic radiation in civil aircraft flights. Special mention is made of computer simulations of the radiation environment as a means of predicting necessary control measures, of the reliability and integration of radiation measuring devices into control procedures and of the relevance of different access control procedures. (author)

Control Structure Design of an Innovative Enhanced Biological Nutrient Recovery Activated Sludge System Coupled with a Photobioreactor

DEFF Research Database (Denmark)

Valverde Perez, Borja; Fuentes-Martínez, José Manuel; Flores Alsina, Xavier

2015-01-01

The TRENS system is a train of biological units designed for resource recovery from wastewater. It is a sequence of a modified enhanced biological phosphorus removal and recovery system (EBP2R) coupled with a photobioreactor (PBR). The bacteria-based system constructs an optimal culture media...... for the downstream algae cultivation. In this work, we present a control strategy to ensure an optimal nutrient balance to feed to the PBR, so the grown algal suspension is suitable for fertigation (irrigation and fertilization of agricultural crops). The system is able to recover up to 75% of the influent load......, while keeping an optimal N-to-P ratio of 16 in the influent to the PBR. The system is tested under different scenarios, where the influent quality is disturbed following a step change. The control system is able to reject most of the disturbances. However, when the P-recovery is limited by the bacteria...

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.

Population and prehistory II: space-limited human populations in constant environments.

Science.gov (United States)

Puleston, Cedric O; Tuljapurkar, Shripad

2008-09-01

We present a population model to examine the forces that determined the quality and quantity of human life in early agricultural societies where cultivable area is limited. The model is driven by the non-linear and interdependent relationships between the age distribution of a population, its behavior and technology, and the nature of its environment. The common currency in the model is the production of food, on which age-specific rates of birth and death depend. There is a single non-trivial equilibrium population at which productivity balances caloric needs. One of the most powerful controls on equilibrium hunger level is fertility control. Gains against hunger are accompanied by decreases in population size. Increasing worker productivity does increase equilibrium population size but does not improve welfare at equilibrium. As a case study we apply the model to the population of a Polynesian valley before European contact.

The nutritional adequacy of a limited vegan diet for a controlled ecological life-support system

Science.gov (United States)

Saha, P. R.; Trumbo, P. R.

Purdue University, as well as the Johnson and Kennedy Space Centers and NASA Ames Research Center, are investigating approximately 5-10 plants that will be grown hydroponically to provide not only the energy and nutrients, but also the oxygen for humans habitating in Mars and lunar bases. The growth and nutritional status of rats fed either a control diet (adequate in all macro- and micronutrients) or a strict vegetarian diet consisting of 5 (vegan-5) or 10 (vegan-10) candidate crop species were investigated. In addition, vegan-10 diets were supplemented with mineral and/or vitamin mix at a level similar to the control diets to assess the effect of supplementation on nutrient status. The assessment of inedible plant material as an alternative food source was also investigated. Results of this study demonstrated that consumption of the vegan-10 diet significantly improved weight gain of rats compared to that for rats fed the vegan-5 diet. Mineral supplementation, at a level present in the control diet, to the vegan-10 diet improved growth and nutrient status, but growth was significantly lower compared to the control-fed rats. Inclusion of inedible plant material, high in ash content, improved some indices of nutrient status, without improving growth.

Kinetic start-up performance of two large treatment plants for nutrient removal

DEFF Research Database (Denmark)

Haarbo, A.; Harremoës, Poul; Thirsing, C.

2001-01-01

In 1987 an action plan was passed in the Danish Parliament demanding a considerable reduction of the discharge of nutrients to the aquatic environment in Denmark. Consequently, the two largest wastewater treatment plants in the Copenhagen area had to be upgraded to include nutrient removal....... For more than 8 years an extensive effort has been made to determine an optimum solution for this upgrading from a technical and financial point of view. The work included six years of comprehensive pilot plant investigations with the aim of thoroughly studying and interpreting the kinetics...... of the processes involved. The investigations revealed valuable information particularly concerning limitations of the nitrification process. Consequently, the investigations contributed to an expectation of no unforeseen problems during the implementation of the upgraded plants. This paper presents the results...

Multiple Transceptors for Macro- and Micro-Nutrients Control Diverse Cellular Properties Through the PKA Pathway in Yeast: A Paradigm for the Rapidly Expanding World of Eukaryotic Nutrient Transceptors Up to Those in Human Cells.

Science.gov (United States)

Steyfkens, Fenella; Zhang, Zhiqiang; Van Zeebroeck, Griet; Thevelein, Johan M

2018-01-01

The nutrient composition of the medium has dramatic effects on many cellular properties in the yeast Saccharomyces cerevisiae . In addition to the well-known specific responses to starvation for an essential nutrient, like nitrogen or phosphate, the presence of fermentable sugar or a respirative carbon source leads to predominance of fermentation or respiration, respectively. Fermenting and respiring cells also show strong differences in other properties, like storage carbohydrate levels, general stress tolerance and cellular growth rate. However, the main glucose repression pathway, which controls the switch between respiration and fermentation, is not involved in control of these properties. They are controlled by the protein kinase A (PKA) pathway. Addition of glucose to respiring yeast cells triggers cAMP synthesis, activation of PKA and rapid modification of its targets, like storage carbohydrate levels, general stress tolerance and growth rate. However, starvation of fermenting cells in a glucose medium for any essential macro- or micro-nutrient counteracts this effect, leading to downregulation of PKA and its targets concomitant with growth arrest and entrance into G0. Re-addition of the lacking nutrient triggers rapid activation of the PKA pathway, without involvement of cAMP as second messenger. Investigation of the sensing mechanism has revealed that the specific high-affinity nutrient transporter(s) induced during starvation function as transporter-receptors or transceptors for rapid activation of PKA upon re-addition of the missing substrate. In this way, transceptors have been identified for amino acids, ammonium, phosphate, sulfate, iron, and zinc. We propose a hypothesis for regulation of PKA activity by nutrient transceptors to serve as a conceptual framework for future experimentation. Many properties of transceptors appear to be similar to those of classical receptors and nutrient transceptors may constitute intermediate forms in the development

Multiple Transceptors for Macro- and Micro-Nutrients Control Diverse Cellular Properties Through the PKA Pathway in Yeast: A Paradigm for the Rapidly Expanding World of Eukaryotic Nutrient Transceptors Up to Those in Human Cells

Directory of Open Access Journals (Sweden)

Fenella Steyfkens

2018-03-01

Full Text Available The nutrient composition of the medium has dramatic effects on many cellular properties in the yeast Saccharomyces cerevisiae. In addition to the well-known specific responses to starvation for an essential nutrient, like nitrogen or phosphate, the presence of fermentable sugar or a respirative carbon source leads to predominance of fermentation or respiration, respectively. Fermenting and respiring cells also show strong differences in other properties, like storage carbohydrate levels, general stress tolerance and cellular growth rate. However, the main glucose repression pathway, which controls the switch between respiration and fermentation, is not involved in control of these properties. They are controlled by the protein kinase A (PKA pathway. Addition of glucose to respiring yeast cells triggers cAMP synthesis, activation of PKA and rapid modification of its targets, like storage carbohydrate levels, general stress tolerance and growth rate. However, starvation of fermenting cells in a glucose medium for any essential macro- or micro-nutrient counteracts this effect, leading to downregulation of PKA and its targets concomitant with growth arrest and entrance into G0. Re-addition of the lacking nutrient triggers rapid activation of the PKA pathway, without involvement of cAMP as second messenger. Investigation of the sensing mechanism has revealed that the specific high-affinity nutrient transporter(s induced during starvation function as transporter-receptors or transceptors for rapid activation of PKA upon re-addition of the missing substrate. In this way, transceptors have been identified for amino acids, ammonium, phosphate, sulfate, iron, and zinc. We propose a hypothesis for regulation of PKA activity by nutrient transceptors to serve as a conceptual framework for future experimentation. Many properties of transceptors appear to be similar to those of classical receptors and nutrient transceptors may constitute intermediate forms in

System-Wide Water Resources Program Nutrient Sub-Model (SWWRP-NSM) Version 1.1

Science.gov (United States)

2008-09-01

in solution Thrm by the mixing of rainwater with soil solution . A rate-limited mass transfer at the soil overland flow interface controls the...dissolved nutrient transfer from soil solution to overland flow, once formed. The mass transfer coefficient will be affected by many factors including

Specialization to Extremely Low-Nutrient Soils Limits the Nutritional Adaptability of Plant Lineages.

Science.gov (United States)

Verboom, G Anthony; Stock, William D; Cramer, Michael D

2017-06-01

Specialization to extreme selective situations promotes the acquisition of traits whose coadaptive integration may compromise evolutionary flexibility and adaptability. We test this idea in the context of the foliar stoichiometry of plants native to the South African Cape. Whereas foliar concentrations of nitrogen, phosphorus (P), potassium (K), calcium, magnesium, and sodium showed strong phylogenetic signal, as did the foliar ratios of these nutrients to P, the same was not true of the corresponding soil values. In addition, although foliar traits were often related to soil values, the coefficients of determination were consistently low. These results identify foliar stoichiometry as having a strong genetic component, with variation in foliar nutrient concentrations, especially [P] and [K], being identified as potentially adaptive. Comparison of stoichiometric variation across 11 similarly aged clades revealed consistently low foliar nutrient concentrations in lineages showing specialization to extremely low-nutrient fynbos heathlands. These lineages also display lower rates of evolution of these traits as well as a reduced tendency for foliar [P] to track soil [P]. Reduced evolutionary lability and adaptability in the nutritional traits of fynbos-specialist lineages may explain the floristic distinctness of the fynbos flora and implies a reduced scope for edaphically driven ecological speciation.

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

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.

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.

Work Environment Dialogue in a Swedish Municipality — Strengths and Limits of the Nordic Work Environment Model

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Kaj Frick

2013-01-01

Full Text Available In the Nordic work environment model, health risks at work are mainly to be managed in cooperation with the employees and their representatives. The model is based on strong trade unions and is supported by the state through participatory rights and funding to produce and disseminate knowledge on risks and solutions. The model is evident in the large Swedish municipal sector with its strong unions and extensive social dialogue. However, municipal employees also face widespread risks, mainly from mental and physical overload. They led the costly wave of rising sickness absence from the late 1990s. Municipal (and other employers therefore attempt to reduce the absence. The rural municipality of Leksand started a project Hälsosam with the broad objectives to half the absence, implement a national agreement on better dialogue, make Leksand an attractive employer, and improve employee influence and work environment. The article’s objective is to use Hälsosam’s intervention project to explore the limits of what the Nordic work environment model can achieve against risks rooted in the employers’ prerogative of organizing, resourcing, and managing the operations that create the conditions at work. Hälsosam’s practice focused on sickness absence and the forms of the new national agreement. The absence was halved by reducing cases of long-term sickness. There was also workplace health promotion and the safety reps were supported through regular meetings. However, little was done to the extensive mental and physical overload revealed in a survey. Nor was the mandatory work environment management improved, as was ordered by the municipal council. This remained delegated to first-line managers who had a limited ability to handle work risks. This limited practice implemented Leksand’s political priority to reduce the absenteeism, while other objectives had less political support. The difficulties to improve the work environment and its management

Nitrogenase (nifH gene expression in diazotrophic cyanobacteria in the Tropical North Atlantic in response to nutrient amendments

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Kendra A Turk-Kubo

2012-11-01

Full Text Available The Tropical North Atlantic (TNAtl plays a critical role in the marine nitrogen cycle, as it supports high rates of biological nitrogen (N2 fixation, yet it is unclear whether this process is limited by the availability of iron (Fe, phosphate (P or is co-limited by both. In order to investigate the impact of nutrient limitation on the N2-fixing microorganisms (diazotrophs in the TNAtl, trace metal clean nutrient amendment experiments were conducted, and the expression of nitrogenase (nifH in cyanobacterial diazotrophs in response to the addition of Fe, P, or Fe+P was measured using quantitative PCR. To provide context, N2 fixation rates associated with the <10 μm community and diel nifH expression in natural cyanobacterial populations were measured. In the western TNAtl, nifH expression in Crocosphaera, Trichodesmium, and Richelia was stimulated by Fe and Fe+P additions, but not by P, implying that diazotrophs may be Fe-limited in this region. In the eastern TNAtl, nifH expression in unicellular cyanobacteria UCYN-A and Crocosphaera was stimulated by P, implying P-limitation. In equatorial waters, nifH expression in Trichodesmium was highest in Fe+P treatments, implying co-limitation in this region. Nutrient additions did not measurably stimulate N2 fixation rates in the <10 μm fraction in most of the experiments, even when upregulation of nifH expression was evident. These results demonstrate the utility of using gene expression to investigate the physiological state of natural populations of microorganisms, while underscoring the complexity of nutrient limitation on diazotrophy, and providing evidence that diazotroph populations are slow to respond to the addition of limiting nutrients and may be limited by different nutrients on basin-wide spatial scales. This has important implications for our current understanding of controls on N2 fixation in the TNAtl and may partially explain why it appears to be intermittently limited by Fe, P, or

Convenience stores are the key food environment influence on nutrients available from household food supplies in Texas Border Colonias

OpenAIRE

Sharkey, Joseph R; Dean, Wesley R; Nalty, Courtney C; Xu, Jin

2013-01-01

Abstract Background Few studies have focused on the relationship between the retail food environment and household food supplies. This study examines spatial access to retail food stores, food shopping habits, and nutrients available in household food supplies among 50 Mexican-origin families residing in Texas border colonias. Methods The design was cross-sectional; data were collected in the home March to June 2010 by promotora-researchers. Ground-truthed methods enumerated traditional (supe...

Effects of Urban Stormwater Infrastructure and Spatial Scale on Nutrient Export and Runoff from Semi-Arid Urban Catchments

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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

40 CFR Table 1 to Subpart IIIi of... - Operating Limits for Capture Systems and Add-On Control Devices

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Operating Limits for Capture Systems... 63—Operating Limits for Capture Systems and Add-On Control Devices If you are required to comply with operating limits by § 63.3093, you must comply with the applicable operating limits in the following table...

Physical determinants of phytoplankton production, algal stoichiometry, and vertical nutrient fluxes.

Science.gov (United States)

Jäger, Christoph G; Diehl, Sebastian; Emans, Maximilian

2010-04-01

Most phytoplankters face opposing vertical gradients in light versus nutrient supplies but have limited capacities for vertical habitat choice. We therefore explored a dynamical model of negatively buoyant algae inhabiting a one-dimensional water column to ask how water column depth and turbulence constrain total (areal) phytoplankton biomass. We show that the population persistence boundaries in water column depth-turbulence space are set by sinking losses and light limitation but that nutrients are most limiting to total biomass in water columns that are neither too shallow or too weakly mixed (where sinking losses prevail) nor too deep and turbulent (where light limitation prevails). In shallow waters, the most strongly limiting process is nutrient influx to the bottom of the water column (e.g., from sediments). In deep waters, the most strongly limiting process is turbulent upward transport of nutrients to the photic zone. Consequently, the highest total biomasses are attained in turbulent waters at intermediate water column depths and in deep waters at intermediate turbulences. These patterns are insensitive to the assumption of fixed versus flexible algal carbon-to-nutrient stoichiometry, and they arise irrespective of whether the water column is a surface layer above a deep water compartment or has direct contact with sediments.

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

internal innovation processes. Open innovation incorporates processes such as 'user-led' (farmer and advisor) innovation and the 'co-development' (by technologists and users) of a technology. This strategy is increasingly used by a variety of organisations across sectors to try to ensure that the use of their outputs (products/services/technologies) is optimised by their target customers/clients, by incorporating user insights into the development of outputs. This research use the open innovation co-development framework through farmer and farm advisor focus group sessions to inform the development of a desirable software package for nutrient management planners (farm advisors) and desirable output formats for the end user (farmers). References Sutton, M., Oenema, O., Erisman, J. W., Leip, A., Grinsven, H. & Winiwarter, W. 2011. Too much of a good thing. Nature, 472, 159.161. European Environment Agency, 2012. European waters — assessment of status and pressures. Environmental Protection Agency, 2012. Ireland's Environment: An assessment 2012. Ribaudo, M.O., Heimlich, R., Claassen, R., Peters, M., 2001. Least-cost management of nonpoint source pollution: source reduction versus interception strategies for controlling nitrogen loss in the Mississippi Basin. Ecological Economics, 37, 183-197.

Do elevated nutrients and organic carbon on Philippine reefs increase the prevalence of coral disease?

Science.gov (United States)

Kaczmarsky, L.; Richardson, L. L.

2011-03-01

Characterizations of Philippine coral diseases are very limited. The two most common, ulcerative white spot disease (UWS) and massive Porites growth anomalies (MPGA), target the genus Porites, a dominant reef-building genus. This is the first investigation in the Philippines to detect positive correlations between coral disease, nutrient levels, and organic carbon. A total of 5,843 Porites colonies were examined. Water and sediment samples were collected for analyses of nutrients (total nitrogen and phosphorus) and total organic carbon at 15 sites along a 40.5 km disease gradient, which was previously shown to positively correlate with human population levels. Results suggest that outbreaks of UWS and MPGAs are driven by elevated nutrient and organic carbon levels. Although the variables analyzed could be proxies for other causative agents (e.g., high sediment levels), the results provide quantitative evidence linking relatively higher coral disease prevalence to an anthropogenically impacted environment.

Nutrient availability constrains the hydraulic architecture and water relations of savannah trees.

Science.gov (United States)

S.J. Bucci; F.G. Scholz; G. Goldstein; F.C. Meinzer; A.C. Franco; P.I. Campanello; R. Villalobos-Vega; M. Bustamante; F. Miralles-Wilhelm

2006-01-01

Several plant functional traits were studied in five dominant woody savanna species in a Brazilian savanna to determine whether removal of nutrient limitations has an effect on carbon allocation, water relations, and hydraulic architecture. Four treatments consisting of a control, and nitrogen (N), phosphorus (P), and N plus P additions were maintained for 5 years....

Rhizosphere priming: a nutrient perspective

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Feike Auke Dijkstra

2013-07-01

Full Text Available Rhizosphere priming is the change in decomposition of soil organic matter (SOM caused by root activity. Rhizosphere priming plays a crucial role in soil carbon (C dynamics and their response to global climate change. Rhizosphere priming may be affected by soil nutrient availability, but rhizosphere priming itself can also affect nutrient supply to plants. These interactive effects may be of particular relevance in understanding the sustained increase in plant growth and nutrient supply in response to a rise in atmospheric CO2 concentration. We examined how these interactions were affected by elevated CO2 in two similar semiarid grassland field studies. We found that an increase in rhizosphere priming enhanced the release of nitrogen (N through decomposition of a larger fraction of SOM in one study, but not in the other. We postulate that rhizosphere priming may enhance N supply to plants in systems that are N limited, but that rhizosphere priming may not occur in systems that are phosphorus (P limited. Under P limitation, rhizodeposition may be used for mobilisation of P, rather than for decomposition of SOM. Therefore, with increasing atmospheric CO2 concentrations, rhizosphere priming may play a larger role in affecting C sequestration in N poor than in P poor soils.

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.

Phosphate limitation induces sporulation in the chytridiomycete Blastocladiella emersonii.

Science.gov (United States)

Bongiorno, Vagner Alexandre; Ferreira da Cruz, Angela; Nunis da Silva, Antonio; Corrêa, Luiz Carlos

2012-09-01

The cell cycle is controlled by numerous mechanisms that ensure correct cell division. If growth is not possible, cells may eventually promote autophagy, differentiation, or apoptosis. Microorganisms interrupt their growth and differentiate under general nutrient limitation. We analyzed the effects of phosphate limitation on growth and sporulation in the chytridiomycete Blastocladiella emersonii using kinetic data, phase-contrast, and laser confocal microscopy. Under phosphate limitation, zoospores germinated and subsequently formed 2-4 spores, regardless of the nutritional content of the medium. The removal of phosphate at any time during growth induced sporulation of vegetative cells. If phosphate was later added to the same cultures, growth was restored if the cells were not yet committed to sporulation. The cycles of addition and withdrawal of phosphate from growth medium resulted in cycles of germination-growth, germination-sporulation, or germination-growth-sporulation. These results show that phosphate limitation is sufficient to interrupt cell growth and to induce complete sporulation in B. emersonii. We concluded that the determination of growth or sporulation in this microorganism is linked to phosphate availability when other nutrients are not limiting. This result provides a new tool for the dissection of nutrient-energy and signal pathways in cell growth and differentiation.

Out of the shadows : multiple nutrient limitations drive relationships among biomass, light and plant diversity

NARCIS (Netherlands)

Harpole, W. Stanley; Sullivan, Lauren L.; Lind, Eric M.; Firn, Jennifer; Adler, Peter B.; Borer, Elizabeth T.; Chase, Jonathan; Fay Jennifer Firn, Philip A.; Hautier, Yann; Hillebrand, Helmut; MacDougall, Andrew S.; Seabloom, Eric W.; Bakker, Jonathan D.; Cadotte, Marc W; Chaneton, Enrique J; Chu, Chengjin; Hagenah, Nicole; Kirkman, Kevin; La Pierre, Kimberly J.; Moore, Joslin L.; Morgan, John W.; Prober, Suzanne M.; Risch, Anita C.; Schuetz, Martin; Stevens, Carly J.

2017-01-01

The paradigmatic hypothesis for the effect of fertilisation on plant diversity represents a one-dimensional trade-off for plants competing for below-ground nutrients (generically) and above-ground light: fertilisation reduces competition for nutrients while increasing biomass and thereby shifts

Limits for the release of uranium compounds to the environment

International Nuclear Information System (INIS)

Lopez, F.; Ferruz, P.; Aguayo, A.

1987-01-01

A conservative criteria to be be followed by a Regulatory Body, in order to provide the limits of radioactive material release in the environment, When all the parameters are not available for the optimization of radiation protection is presented. This criteria can be applied to stablishment of radioactive release limits for uranium compounds from the nuclear fuel cycle facilities. (author)

Radiation monitoring in the NPP environment, control of radioactivity in NPP-environment system

International Nuclear Information System (INIS)

Egorov, Yu.A.

1987-01-01

Problems of radiation monitoring and control of the NPP-environment system (NPPES) are considered. Radiation control system at the NPP and in the environment provides for the control of the NPP, considered as the source of radioactive releases in the environment and for the environmental radiation climate control. It is shown, that the radiation control of the NPP-environment system must be based on the ecological normalization principles of the NPP environmental impacts. Ecological normalization should be individual for the NPP region of each ecosystem. The necessity to organize and conduct radiation ecological monitoring in the NPP regions is pointed out. Radiation ecological monitoring will provide for both environmental current radiation control and information for mathematical models, used in the NPPES radiation control

Foliar nutrient analysis of sugar maple decline: retrospective vector diagnosis

Science.gov (United States)

Victor R. Timmer; Yuanxin Teng

1999-01-01

Accuracy of traditional foiiar analysis of nutrient disorders in sugar maple (Acer saccharum Marsh) is limited by lack of validation and confounding by nutrient interactions. Vector nutrient diagnosis is relatively free of these problems. The technique is demonstrated retrospectively on four case studies. Diagnostic interpretations consistently...

Convenience stores are the key food environment influence on nutrients available from household food supplies in Texas Border Colonias.

Science.gov (United States)

Sharkey, Joseph R; Dean, Wesley R; Nalty, Courtney C; Xu, Jin

2013-01-17

Few studies have focused on the relationship between the retail food environment and household food supplies. This study examines spatial access to retail food stores, food shopping habits, and nutrients available in household food supplies among 50 Mexican-origin families residing in Texas border colonias. The design was cross-sectional; data were collected in the home March to June 2010 by promotora-researchers. Ground-truthed methods enumerated traditional (supercenters, supermarkets, grocery stores), convenience (convenience stores and food marts), and non-traditional (dollar stores, discount stores) retail food stores. Spatial access was computed using the network distance from each participant's residence to each food store. Data included survey data and two household food inventories (HFI) of the presence and amount of food items in the home. The Spanish language interviewer-administered survey included demographics, transportation access, food purchasing, food and nutrition assistance program participation, and the 18-item Core Food Security Module. Nutrition Data Systems for Research (NDS-R) was used to calculate HFI nutrients. Adult equivalent adjustment constants (AE), based on age and gender calorie needs, were calculated based on the age- and gender composition of each household and used to adjust HFI nutrients for household composition. Data were analyzed using bivariate analysis and linear regression models to determine the association of independent variables with the availability of each AE-adjusted nutrient. Regression models showed that households in which the child independently purchased food from a convenience store at least once a week had foods and beverages with increased amounts of total energy, total fat, and saturated fat. A greater distance to the nearest convenience store was associated with reduced amounts of total energy, vitamin D, total sugar, added sugar, total fat, and saturated fat. Participation in the National School Lunch

Water Quality Protection from Nutrient Pollution: Case ...

Science.gov (United States)

Water bodies and coastal areas around the world are threatened by increases in upstream sediment and nutrient loads, which influence drinking water sources, aquatic species, and other ecologic functions and services of streams, lakes, and coastal water bodies. For example, increased nutrient fluxes from the Mississippi River Basin have been linked to increased occurrences of seasonal hypoxia in northern Gulf of Mexico. Lake Erie is another example where in the summer of 2014 nutrients, nutrients, particularly phosphorus, washed from fertilized farms, cattle feedlots, and leaky septic systems; caused a severe algae bloom, much of it poisonous; and resulted in the loss of drinking water for a half-million residents. Our current management strategies for point and non-point source nutrient loadings need to be improved to protect and meet the expected increased future demands of water for consumption, recreation, and ecological integrity. This presentation introduces management practices being implemented and their effectiveness in reducing nutrient loss from agricultural fields, a case analysis of nutrient pollution of the Grand Lake St. Marys and possible remedies, and ongoing work on watershed modeling to improve our understanding on nutrient loss and water quality. Presented at the 3rd International Conference on Water Resource and Environment.

Synergistic effects of pCO2 and iron availability on nutrient consumption ratio of the Bering Sea phytoplankton community

Directory of Open Access Journals (Sweden)

K. Sugie

2013-10-01

Full Text Available Little is known concerning the effect of CO2 on phytoplankton ecophysiological processes under nutrient and trace element-limited conditions, because most CO2 manipulation experiments have been conducted under elements-replete conditions. To investigate the effects of CO2 and iron availability on phytoplankton ecophysiology, we conducted an experiment in September 2009 using a phytoplankton community in the iron limited, high-nutrient, low-chlorophyll (HNLC region of the Bering Sea basin . Carbonate chemistry was controlled by the bubbling of the several levels of CO2 concentration (180, 380, 600, and 1000 ppm controlled air, and two iron conditions were established, one with and one without the addition of inorganic iron. We demonstrated that in the iron-limited control conditions, the specific growth rate and the maximum photochemical quantum efficiency (Fv/Fm of photosystem (PS II decreased with increasing CO2 levels, suggesting a further decrease in iron bioavailability under the high-CO2 conditions. In addition, biogenic silica to particulate nitrogen and biogenic silica to particulate organic carbon ratios increased from 2.65 to 3.75 and 0.39 to 0.50, respectively, with an increase in the CO2 level in the iron-limited controls. By contrast, the specific growth rate, Fv/Fm values and elemental compositions in the iron-added treatments did not change in response to the CO2 variations, indicating that the addition of iron canceled out the effect of the modulation of iron bioavailability due to the change in carbonate chemistry. Our results suggest that high-CO2 conditions can alter the biogeochemical cycling of nutrients through decreasing iron bioavailability in the iron-limited HNLC regions in the future.

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.

Review on Periphyton as Mediator of Nutrient Transfer in Aquatic Ecosystems

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Surjya K. Saikia

2011-12-01

Full Text Available In the studies of aquatic ecology, periphyton has been uncared for despite its vital role in nutrient uptake and transfer to the upper trophic organisms. Being the component of food chain as attached organism it takes part in nutrient cycling in the ecosystem like that of suspended planktonic counterparts. The present review, with an aim to understand the role of periphyton in nutrient transfer from benthic environment to upper trophic level, focuses many aspects of periphyton-nutrient relationship based on available literatures. It also attempts to redefine periphyton, as a part of biofilm, harboring nutrient components like protein, fat and carbohydrate preferably in its extracellular polymeric substance (EPS, cyanobacteria, diatom and other algal communities. In addition to physical processes, nutrient uptake by periphyton is catalyzed by enzymes like Nitrogen Reductase and Alkaline Phosphatase from the environment. This uptake and transfer is further regulated by periphytic C: nutrient (N or P stoichiometry, colonization time, distribution of periphyton cover on sediments and macrophytes, macronutrient concentration, grazing, sloughing, temperature, and advective transport. The Carbon (C sources of periphyton are mainly dissolve organic matter and photosynthetic C that enters into higher trophic levels through predation and transfers as C-rich nutrient components. Despite of emerging interests on utilizing periphyton as nutrient transfer tool in aquatic ecosystem, the major challenges ahead for modern aquatic biologists lies on determining nutrient uptake and transfer rate of periphyton, periphytic growth and simulating nutrient models of periphyton to figure a complete energy cycle in aquatic ecosystem.

Linking nutrient enrichment, sediment erodibility and biofilms

Science.gov (United States)

Conrad, B.; Mahon, R.; Sojka, S. L.

2014-12-01

Sediment movement in coastal lagoons affects nutrient flux and primary producer growth. Previous research has shown that sediment erodibility is affected by biofilm concentration and that growth of benthic organisms, which produce biofilm, is affected by nutrient enrichment. However, researchers have not examined possible links between nutrient addition and sediment erodibility. We manipulated nutrient levels in the water column of 16 microcosms filled with homogenized sediment from a shallow coastal lagoon and artificial seawater to determine the effects on biofilm growth, measured through chlorophyll a and colloidal carbohydrate concentrations. Erosion tests using a Gust microcosm were conducted to determine the relationship between sediment erodibility and biofilm concentration. Results show that carbohydrate levels decreased with increasing nutrient enrichment and were unrelated to chlorophyll concentrations and erodibility. The nutrient levels did not predictably affect the chlorophyll levels, with lower chlorophyll concentrations in the control and medium enrichment treatments than the low and high enrichment treatments. Controls on biofilm growth are still unclear and the assumed relationship between carbohydrates and erodibility may be invalid. Understanding how biofilms respond to nutrient enrichment and subsequent effects on sediment erodibility is essential for protecting and restoring shallow coastal systems.

Production, partitioning and stoichiometry of organic matter under variable nutrient supply during mesocosm experiments in the tropical Pacific and Atlantic Ocean

Directory of Open Access Journals (Sweden)

J. M. S. Franz

2012-11-01

Full Text Available Oxygen-deficient waters in the ocean, generally referred to as oxygen minimum zones (OMZ, are expected to expand as a consequence of global climate change. Poor oxygenation is promoting microbial loss of inorganic nitrogen (N and increasing release of sediment-bound phosphate (P into the water column. These intermediate water masses, nutrient-loaded but with an N deficit relative to the canonical N:P Redfield ratio of 16:1, are transported via coastal upwelling into the euphotic zone. To test the impact of nutrient supply and nutrient stoichiometry on production, partitioning and elemental composition of dissolved (DOC, DON, DOP and particulate (POC, PON, POP organic matter, three nutrient enrichment experiments were conducted with natural microbial communities in shipboard mesocosms, during research cruises in the tropical waters of the southeast Pacific and the northeast Atlantic. Maximum accumulation of POC and PON was observed under high N supply conditions, indicating that primary production was controlled by N availability. The stoichiometry of microbial biomass was unaffected by nutrient N:P supply during exponential growth under nutrient saturation, while it was highly variable under conditions of nutrient limitation and closely correlated to the N:P supply ratio, although PON:POP of accumulated biomass generally exceeded the supply ratio. Microbial N:P composition was constrained by a general lower limit of 5:1. Channelling of assimilated P into DOP appears to be the mechanism responsible for the consistent offset of cellular stoichiometry relative to inorganic nutrient supply and nutrient drawdown, as DOP build-up was observed to intensify under decreasing N:P supply. Low nutrient N:P conditions in coastal upwelling areas overlying O₂-deficient waters seem to represent a net source for DOP, which may stimulate growth of diazotrophic phytoplankton. These results demonstrate that microbial nutrient assimilation and

A targeted management of the nutrient solution in a soilless tomato crop according to plant needs

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Angelo eSignore

2016-03-01

Full Text Available The adoption of closed soilless systems is useful in minimizing the environmental impact of the greenhouse crops. Instead, a significant problem in closed soilless systems is represented by the accumulation of ions in the recycled nutrient solution, in particular the unabsorbed or poorly absorbed ones. To overcome such problem, we: 1 studied the effect of several values of the electrical conductivity (EC of nutrient solution in a NFT (Nutrient Film Technique system on a cherry type tomato crop, and 2 define a NS (called recovery solution, based on the concept of uptake concentration and transpiration-biomass ratio, that fits the real needs of the plant with respect to water and nutrients. Three levels of EC set point (SP, above which the NS was completely replaced (SP5, SP7.5, and SP10 for the EC limit of 5, 7.5 and 10 dS m-1, respectively, were established. The SP10 treatment yield was not different from other treatments, and it allowed a better quality of the berries (for dry matter and total soluble solids and higher environmental sustainability due to a lower discharge of total nutrients into the environment (37 and 59% with respect to SP7.5 and SP5, respectively.The recovery solution used in the second trial allowed a more punctual NS management, by adapting to the real needs of the crop. Moreover, it allowed a lesser amount of water and nutrients to be discharged into the environment and a better use of brackish water, due to a more accurate management of the EC of the NS. The targeted management, based on transpiration-biomass ratio, indicates that, in some stages of the plant cycle, the nutrient solution used can be diluted, in order to save water and nutrients. With such management a closed cycle can be realized without affecting the yield, but improving the quality of the tomato berries.

Nutrient budgets for large Chinese estuaries

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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

Physiological strategies of co-occurring oaks in a water- and nutrient-limited ecosystem

Science.gov (United States)

Heidi Renninger; Nicholas Carlo; Kenneth L. Clark; Karina V.R. Schafer

2014-01-01

Oak species are well suited to water-limited conditions by either avoiding water stress through deep rooting or tolerating water stress through tight stomatal control. In co-occurring species where resources are limited, species may either partition resources in space and/or time or exhibit differing efficiencies in the use of limited resources. Therefore, this study...

Mycobacterium fortuitum and Mycobacterium chelonae biofilm formation under high and low nutrient conditions.

Science.gov (United States)

Hall-Stoodley, L; Keevil, C W; Lappin-Scott, H M

1998-12-01

The rapidly growing mycobacteria (RGM) are broadly disbursed in the environment. They have been recovered from freshwater, seawater, wastewater and even potable water samples and are increasingly associated with non-tuberculous mycobacterial disease. There is scant evidence that non-tuberculous mycobacteria (NTM) and RGM form biofilms. Therefore, an experimental system was designed to assess the ability of RGM to form biofilms under controlled laboratory conditions. A flat plate reactor flow cell was attached to either a high or low nutrient reservoir and monitored by image analysis over time. Two surfaces were chosen for assessment of biofilm growth: silastic which is commonly used in medical settings and high density polyethylene (HDPE) which is prevalent in water distribution systems. The results show that Mycobacterium fortuitum and M. chelonae formed biofilms under both high and low nutrient conditions on both surfaces studied. These results suggest that RGM may form biofilms under a variety of conditions in industrial and medical environments. 1998 Society of Applied Microbiology.

The Stoichiometry of Nutrient Release by Terrestrial Herbivores and Its Ecosystem Consequences

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Judith Sitters

2017-04-01

Full Text Available It is widely recognized that the release of nutrients by herbivores via their waste products strongly impacts nutrient availability for autotrophs. The ratios of nitrogen (N and phosphorus (P recycled through herbivore release (i.e., waste N:P are mainly determined by the stoichiometric composition of the herbivore's food (food N:P and its body nutrient content (body N:P. Waste N:P can in turn impact autotroph nutrient limitation and productivity. Herbivore-driven nutrient recycling based on stoichiometric principles is dominated by theoretical and experimental research in freshwater systems, in particular interactions between algae and invertebrate herbivores. In terrestrial ecosystems, the impact of herbivores on nutrient cycling and availability is often limited to studying carbon (C:N and C:P ratios, while the role of terrestrial herbivores in mediating N:P ratios is also likely to influence herbivore-driven nutrient recycling. In this review, we use rules and predictions on the stoichiometry of nutrient release originating from algal-based aquatic systems to identify the factors that determine the stoichiometry of nutrient release by herbivores. We then explore how these rules can be used to understand the stoichiometry of nutrient release by terrestrial herbivores, ranging from invertebrates to mammals, and its impact on plant nutrient limitation and productivity. Future studies should focus on measuring both N and P when investigating herbivore-driven nutrient recycling in terrestrial ecosystems, while also taking the form of waste product (urine or feces and other pathways by which herbivores change nutrients into account, to be able to quantify the impact of waste stoichiometry on plant communities.

Nitrogenous nutrients and primary production in a tropical oceanic environment

Digital Repository Service at National Institute of Oceanography (India)

Wafar, M.V.M.; Wafar, S.; Devassy, V.P.

Measurements of the concentrations of nitrogenous nutrients and primary production were made at 10 stations along 8 degrees N and 10 degrees N in the tropical oceanic Lakshadweep waters Inorganic nitrogen (NO3, NO2 and NH4) accounted for less than...

A Computational Study of Amensalistic Control of Listeria monocytogenes by Lactococcus lactis under Nutrient Rich Conditions in a Chemostat Setting

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Hassan Khassehkhan

2016-09-01

Full Text Available We study a previously introduced mathematical model of amensalistic control of the foodborne pathogen Listeria monocytogenes by the generally regarded as safe lactic acid bacteria Lactococcus lactis in a chemostat setting under nutrient rich growth conditions. The control agent produces lactic acids and thus affects pH in the environment such that it becomes detrimental to the pathogen while it is much more tolerant to these self-inflicted environmental changes itself. The mathematical model consists of five nonlinear ordinary differential equations for both bacterial species, the concentration of lactic acids, the pH and malate. The model is algebraically too involved to allow a comprehensive, rigorous qualitative analysis. Therefore, we conduct a computational study. Our results imply that depending on the growth characteristics of the medium in which the bacteria are cultured, the pathogen can survive in an intermediate flow regime but will be eradicated for slower flow rates and washed out for higher flow rates.

Technology Of Controlled-Environment Agriculture

Science.gov (United States)

Bubenheim, David L.; Bates, Maynard E.

1995-01-01

Report discusses controlled-environment agriculture (CEA) for commercial production of organisms, whether plants or animals. Practiced in greenhouses to produce food on nonarable lands. Describes conceptual regenerative system that incorporates biological, physical, and chemical processes to support humans in extraterrestrial environments.

Quantum control limited by quantum decoherence

International Nuclear Information System (INIS)

Xue, Fei; Sun, C. P.; Yu, S. X.

2006-01-01

We describe quantum controllability under the influences of the quantum decoherence induced by the quantum control itself. It is shown that, when the controller is considered as a quantum system, it will entangle with its controlled system and then cause quantum decoherence in the controlled system. In competition with this induced decoherence, the controllability will be limited by some uncertainty relation in a well-armed quantum control process. In association with the phase uncertainty and the standard quantum limit, a general model is studied to demonstrate the possibility of realizing a decoherence-free quantum control with a finite energy within a finite time. It is also shown that if the operations of quantum control are to be determined by the initial state of the controller, then due to the decoherence which results from the quantum control itself, there exists a low bound for quantum controllability

Ocean acidification impacts bacteria-phytoplankton coupling at low-nutrient conditions

Science.gov (United States)

Hornick, Thomas; Bach, Lennart T.; Crawfurd, Katharine J.; Spilling, Kristian; Achterberg, Eric P.; Woodhouse, Jason N.; Schulz, Kai G.; Brussaard, Corina P. D.; Riebesell, Ulf; Grossart, Hans-Peter

2017-01-01

the four fCO2-treated mesocosms from both control mesocosms, indicating that complex trophic interactions might be altered in a future acidified ocean. Possible consequences for nutrient cycling and carbon export are still largely unknown, in particular in a nutrient-limited ocean.

Nitrogen and phosphorus limitation over long-term ecosystem development in terrestrial ecosystems.

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Duncan N L Menge

Full Text Available Nutrient limitation to net primary production (NPP displays a diversity of patterns as ecosystems develop over a range of timescales. For example, some ecosystems transition from N limitation on young soils to P limitation on geologically old soils, whereas others appear to remain N limited. Under what conditions should N limitation and P limitation prevail? When do transitions between N and P limitation occur? We analyzed transient dynamics of multiple timescales in an ecosystem model to investigate these questions. Post-disturbance dynamics in our model are controlled by a cascade of rates, from plant uptake (very fast to litter turnover (fast to plant mortality (intermediate to plant-unavailable nutrient loss (slow to weathering (very slow. Young ecosystems are N limited when symbiotic N fixation (SNF is constrained and P weathering inputs are high relative to atmospheric N deposition and plant N:P demand, but P limited under opposite conditions. In the absence of SNF, N limitation is likely to worsen through succession (decades to centuries because P is mineralized faster than N. Over long timescales (centuries and longer this preferential P mineralization increases the N:P ratio of soil organic matter, leading to greater losses of plant-unavailable N versus P relative to plant N:P demand. These loss dynamics favor N limitation on older soils despite the rising organic matter N:P ratio. However, weathering depletion favors P limitation on older soils when continual P inputs (e.g., dust deposition are low, so nutrient limitation at the terminal equilibrium depends on the balance of these input and loss effects. If NPP switches from N to P limitation over long time periods, the transition time depends most strongly on the P weathering rate. At all timescales SNF has the capacity to overcome N limitation, so nutrient limitation depends critically on limits to SNF.

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

Bioextraction potential of seaweed in Denmark — An instrument for circular nutrient management

International Nuclear Information System (INIS)

Seghetta, Michele; Tørring, Ditte; Bruhn, Annette; Thomsen, Marianne

2016-01-01

The aim of the study is to assess the efficacy of seaweed for circular nutrient management to reduce eutrophication levels in the aquatic environment. We performed a comparative Life Cycle Assessment (LCA) of two reference waste management systems treating seaweed as biowaste, i.e. landfill disposal and combustion, and an alternative scenario using the seaweed Saccharina latissima as a resource for biobased fertilizer production. Life Cycle Impact Assessment (LCIA) methods were improved by using a cradle-to-cradle approach, quantifying fate factors for nitrogen and phosphorus loss from fertilized agriculture to the aquatic environment. We also differentiated between nitrogen- and phosphorus-limited marine water to improve the traditional freshwater impact category, making this indicator suitable for decision support in relation to coastal water management schemes. Offshore cultivation of Saccharina latissima with an average productivity of 150 Mg/km"2 in Danish waters in 2014 was applied to a cultivation scenario of 208 km"2. The bioresource scenario performs better than conventional biowaste management systems, delivering a net reduction in aquatic eutrophication levels of 32.29 kg N eq. and 16.58 kg PO_4"3"− eq. per Mg (dry weight) of seaweed, quantified by the ReCiPe and CML impact assessment methods, respectively. Seaweed cultivation, harvest and reuse of excess nutrients from the aquatic environment is a promising approach for sustainable resource cycling in a future regenerative economy that exploits manmade emissions as a resource for closed loop biobased production while significantly reducing eutrophication levels in 3 out of 7 Danish river basin districts. We obtained at least 10% bioextraction of phosphorus manmade emissions (10%, 89% and > 100%) and contributed significantly to local nitrogen reduction goals according to the Water Framework Directive (23%, 78% and > 100% of the target). - Highlights: • Offshore seaweed production for nutrient

Bioextraction potential of seaweed in Denmark — An instrument for circular nutrient management

Energy Technology Data Exchange (ETDEWEB)

Seghetta, Michele [Research Group on EcoIndustrial System Analysis, Department of Environmental Science, Faculty of Science and Technology, Aarhus University, Frederiksborgvej 399, 4000 Roskilde (Denmark); Tørring, Ditte [Orbicon A/S, Jens Juuls Vej 16, 8260 Viby (Denmark); Bruhn, Annette [Department of Bioscience, Faculty of Science and Technology, Aarhus University, Vejlsøvej 25, 8600 Silkeborg (Denmark); Thomsen, Marianne, E-mail: mth@envs.au.dk [Research Group on EcoIndustrial System Analysis, Department of Environmental Science, Faculty of Science and Technology, Aarhus University, Frederiksborgvej 399, 4000 Roskilde (Denmark)

2016-09-01

The aim of the study is to assess the efficacy of seaweed for circular nutrient management to reduce eutrophication levels in the aquatic environment. We performed a comparative Life Cycle Assessment (LCA) of two reference waste management systems treating seaweed as biowaste, i.e. landfill disposal and combustion, and an alternative scenario using the seaweed Saccharina latissima as a resource for biobased fertilizer production. Life Cycle Impact Assessment (LCIA) methods were improved by using a cradle-to-cradle approach, quantifying fate factors for nitrogen and phosphorus loss from fertilized agriculture to the aquatic environment. We also differentiated between nitrogen- and phosphorus-limited marine water to improve the traditional freshwater impact category, making this indicator suitable for decision support in relation to coastal water management schemes. Offshore cultivation of Saccharina latissima with an average productivity of 150 Mg/km{sup 2} in Danish waters in 2014 was applied to a cultivation scenario of 208 km{sup 2}. The bioresource scenario performs better than conventional biowaste management systems, delivering a net reduction in aquatic eutrophication levels of 32.29 kg N eq. and 16.58 kg PO{sub 4}{sup 3−} eq. per Mg (dry weight) of seaweed, quantified by the ReCiPe and CML impact assessment methods, respectively. Seaweed cultivation, harvest and reuse of excess nutrients from the aquatic environment is a promising approach for sustainable resource cycling in a future regenerative economy that exploits manmade emissions as a resource for closed loop biobased production while significantly reducing eutrophication levels in 3 out of 7 Danish river basin districts. We obtained at least 10% bioextraction of phosphorus manmade emissions (10%, 89% and > 100%) and contributed significantly to local nitrogen reduction goals according to the Water Framework Directive (23%, 78% and > 100% of the target). - Highlights: • Offshore seaweed production

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.

Performance limit of daytime radiative cooling in warm humid environment

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Takahiro Suichi

2018-05-01

Full Text Available Daytime radiative cooling potentially offers efficient passive cooling, but the performance is naturally limited by the environment, such as the ambient temperature and humidity. Here, we investigate the performance limit of daytime radiative cooling under warm and humid conditions in Okayama, Japan. A cooling device, consisting of alternating layers of SiO2 and poly(methyl methacrylate on an Al mirror, is fabricated and characterized to demonstrate a high reflectance for sunlight and a selective thermal radiation in the mid-infrared region. In the temperature measurement under the sunlight irradiation, the device shows 3.4 °C cooler than a bare Al mirror, but 2.8 °C warmer than the ambient of 35 °C. The corresponding numerical analyses reveal that the atmospheric window in λ = 16 ∼ 25 μm is closed due to a high humidity, thereby limiting the net emission power of the device. Our study on the humidity influence on the cooling performance provides a general guide line of how one can achieve practical passive cooling in a warm humid environment.

Flexible Access Control for Dynamic Collaborative Environments

NARCIS (Netherlands)

Dekker, M.A.C.

2009-01-01

Access control is used in computer systems to control access to confidential data. In this thesis we focus on access control for dynamic collaborative environments where multiple users and systems access and exchange data in an ad hoc manner. In such environments it is difficult to protect

Phytoremediation to remove nutrients and improve eutrophic stormwaters using water lettuce (Pistia stratiotes L.).

Science.gov (United States)

Lu, Qin; He, Zhenli L; Graetz, Donald A; Stoffella, Peter J; Yang, Xiaoe

2010-01-01

Water quality impairment by nutrient enrichment from agricultural activities has been a concern worldwide. Phytoremediation technology using aquatic plants in constructed wetlands and stormwater detention ponds is increasingly applied to remediate eutrophic waters. The objectives of this study were to evaluate the effectiveness and potential of water lettuce (Pistia stratiotes L.) in removing nutrients including nitrogen (N) and phosphorus (P) from stormwater in the constructed water detention systems before it is discharged into the St. Lucie Estuary, an important surface water system in Florida, using phytoremediation technologies. In this study, water lettuce (P. stratiotes) was planted in the treatment plots of two stormwater detention ponds (East and West Ponds) in 2005-2007 and water samples from both treatment and control plots were weekly collected and analyzed for water quality properties including pH, electrical conductivity, turbidity, suspended solids, and nutrients (N and P). Optimum plant density was maintained and plant samples were collected monthly and analyzed for nutrient contents. Water quality in both ponds was improved, as evidenced by decreases in water turbidity, suspended solids, and nutrient concentrations. Water turbidity was decreased by more than 60%. Inorganic N (NH(4) (+) and NO(3) (-)) concentrations in treatment plots were more than 50% lower than those in control plots (without plant). Reductions in both PO(4) (3-) and total P were approximately 14-31%, as compared to the control plots. Water lettuce contained average N and P concentrations of 17 and 3.0 g kg(-1), respectively, and removed 190-329 kg N ha(-1) and 25-34 kg P ha(-1) annually. Many aquatic plants have been used to remove nutrients from eutrophic waters but water lettuce proved superior to most other plants in nutrient removal efficiency, owing to its rapid growth and high biomass yield potential. However, the growth and nutrient removal potential are affected by many

Nutrient sensing and TOR signaling in yeast and mammals.

Science.gov (United States)

González, Asier; Hall, Michael N

2017-02-15

Coordinating cell growth with nutrient availability is critical for cell survival. The evolutionarily conserved TOR (target of rapamycin) controls cell growth in response to nutrients, in particular amino acids. As a central controller of cell growth, mTOR (mammalian TOR) is implicated in several disorders, including cancer, obesity, and diabetes. Here, we review how nutrient availability is sensed and transduced to TOR in budding yeast and mammals. A better understanding of how nutrient availability is transduced to TOR may allow novel strategies in the treatment for mTOR-related diseases. © 2017 The Authors.

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)

Convenience stores are the key food environment influence on nutrients available from household food supplies in Texas Border Colonias

Directory of Open Access Journals (Sweden)

Sharkey Joseph R

2013-01-01

Full Text Available Abstract Background Few studies have focused on the relationship between the retail food environment and household food supplies. This study examines spatial access to retail food stores, food shopping habits, and nutrients available in household food supplies among 50 Mexican-origin families residing in Texas border colonias. Methods The design was cross-sectional; data were collected in the home March to June 2010 by promotora-researchers. Ground-truthed methods enumerated traditional (supercenters, supermarkets, grocery stores, convenience (convenience stores and food marts, and non-traditional (dollar stores, discount stores retail food stores. Spatial access was computed using the network distance from each participant’s residence to each food store. Data included survey data and two household food inventories (HFI of the presence and amount of food items in the home. The Spanish language interviewer-administered survey included demographics, transportation access, food purchasing, food and nutrition assistance program participation, and the 18-item Core Food Security Module. Nutrition Data Systems for Research (NDS-R was used to calculate HFI nutrients. Adult equivalent adjustment constants (AE, based on age and gender calorie needs, were calculated based on the age- and gender composition of each household and used to adjust HFI nutrients for household composition. Data were analyzed using bivariate analysis and linear regression models to determine the association of independent variables with the availability of each AE-adjusted nutrient. Results Regression models showed that households in which the child independently purchased food from a convenience store at least once a week had foods and beverages with increased amounts of total energy, total fat, and saturated fat. A greater distance to the nearest convenience store was associated with reduced amounts of total energy, vitamin D, total sugar, added sugar, total fat, and saturated

Convenience stores are the key food environment influence on nutrients available from household food supplies in Texas Border Colonias

Science.gov (United States)

2013-01-01

Background Few studies have focused on the relationship between the retail food environment and household food supplies. This study examines spatial access to retail food stores, food shopping habits, and nutrients available in household food supplies among 50 Mexican-origin families residing in Texas border colonias. Methods The design was cross-sectional; data were collected in the home March to June 2010 by promotora-researchers. Ground-truthed methods enumerated traditional (supercenters, supermarkets, grocery stores), convenience (convenience stores and food marts), and non-traditional (dollar stores, discount stores) retail food stores. Spatial access was computed using the network distance from each participant’s residence to each food store. Data included survey data and two household food inventories (HFI) of the presence and amount of food items in the home. The Spanish language interviewer-administered survey included demographics, transportation access, food purchasing, food and nutrition assistance program participation, and the 18-item Core Food Security Module. Nutrition Data Systems for Research (NDS-R) was used to calculate HFI nutrients. Adult equivalent adjustment constants (AE), based on age and gender calorie needs, were calculated based on the age- and gender composition of each household and used to adjust HFI nutrients for household composition. Data were analyzed using bivariate analysis and linear regression models to determine the association of independent variables with the availability of each AE-adjusted nutrient. Results Regression models showed that households in which the child independently purchased food from a convenience store at least once a week had foods and beverages with increased amounts of total energy, total fat, and saturated fat. A greater distance to the nearest convenience store was associated with reduced amounts of total energy, vitamin D, total sugar, added sugar, total fat, and saturated fat. Participation in

Controlled Environment Specimen Transfer

DEFF Research Database (Denmark)

Damsgaard, Christian Danvad; Zandbergen, Henny W.; Hansen, Thomas Willum

2014-01-01

an environmental transmission electron microscope to an in situ X-ray diffractometer through a dedicated transmission electron microscope specimen transfer holder, capable of sealing the specimen in a gaseous environment at elevated temperatures. Two catalyst material systems have been investigated; Cu/ZnO/Al2O3...... transferred in a reactive environment to the environmental transmission electron microscope where further analysis on the local scale were conducted. The Co/Al2O3 catalyst was reduced in the environmental microscope and successfully kept reduced outside the microscope in a reactive environment. The in situ......Specimen transfer under controlled environment conditions, such as temperature, pressure, and gas composition, is necessary to conduct successive complementary in situ characterization of materials sensitive to ambient conditions. The in situ transfer concept is introduced by linking...

Nutrient dynamics and primary production in a pristine coastal mangrove ecosystem: Andaman Islands, India

Science.gov (United States)

Jenkins, E. N.; Nickodem, K.; Siemann, A. L.; Hoeher, A.; Sundareshwar, P. V.; Ramesh, R.; Purvaja, R.; Banerjee, K.; Manickam, S.; Haran, H.

2012-12-01

Mangrove ecosystems play a key role in supporting coastal food webs and nutrient cycles in the coastal zone. Their strategic position between the land and the sea make them important sites for land-ocean interaction. As part of an Indo-US summer field course we investigated changes in the water chemistry in a pristine mangrove creek located at Wright Myo in the Andaman Islands, India. This study was conducted during the wet season (June 2012) to evaluate the influence of the coastal mangrove wetlands on the water quality and productivity in adjoining pelagic waters. Over a full tidal cycle spanning approximately 24 hrs, we measured nutrient concentrations and other ancillary parameters (e.g. dissolved oxygen, turbidity, salinity, etc.) hourly to evaluate water quality changes in incoming and ebbing tides. Nutrient analyses had the following concentration ranges (μM): nitrite 0.2-0.9, nitrate 2.0-11.5, ammonium 1.3-7.5, dissolved inorganic phosphate 0.7-2.8. The dissolved inorganic nitrogen to dissolved inorganic phosphate (DIN/DIP) ratio was very low relative to an optimal ratio, suggesting growth is nitrogen limited. In addition, we conducted primary production assays to investigate the factors that controlled primary production in this pristine creek. The experiment was carried out in situ using the Winkler method at low and high tide. Four-hour incubation of light and dark bottles representing a fixed control, non-fertilized, fertilized with nitrate, and fertilized with phosphate enabled the measurement of both net oxygen production and dark respiration. The low tide experiment suggests the ecosystem is heterotrophic because the oxygen measured in the light bottles was consistently less than that of the dark bottles. This result may be an experimental artifact of placing the glass bottles in the sun for too long prior to incubation, potentially leading to photolysis of large organic molecules in the light bottles. The high tide experiment also displayed

Phosphorus body content in an herbivorous fish in environments with different trophic state

Directory of Open Access Journals (Sweden)

Talita M. de Andrade Santos

2016-04-01

Full Text Available Animals are believed to be homeostatic by maintaining relatively constant body nutrient content independently of changes in diet. Phosphorus (P is one of the most important elements for fishes as Loricariids, which are covered with armor-like bony plates. These species are expected to maintain nutrient homeostasis, however, in environments with low P availability they can be P-limited. The hypothesis of this study is that P concentration in body composition of an herbivorous fish, Hypostomus jaguribensis, does not change in environments with different availability of this nutrient. We conducted this study in two locations of the Curu river basin in Brazil, which differed in their nutrient concentrations: one was ultraoligotrophic and the other mesotrophic, as determined by total phosphorous concentrations and chlorophyll a in the water. We found significant differences in the body P content of the fish from the two sites: Hypostomus jaguribensis from the ultraoligotrophic site showed higher body P content, higher body weight and condition factor. This suggests that the ultraoligotrophic site is a more favorable environment for this species. The body P content was higher in intermediate sizes (between 12 and 14 cm in the ultraoligotrophic site and between 11 and 13 cm in the mesotrophic site, which can be related to biological characteristics such as the need to accumulate nutrients at the beginning of the reproductive period. Our study did not find support for strict homeostasis in this high-P demand fish species.

Game controller modification for fMRI hyperscanning experiments in a cooperative virtual reality environment.

Science.gov (United States)

Trees, Jason; Snider, Joseph; Falahpour, Maryam; Guo, Nick; Lu, Kun; Johnson, Douglas C; Poizner, Howard; Liu, Thomas T

2014-01-01

Hyperscanning, an emerging technique in which data from multiple interacting subjects' brains are simultaneously recorded, has become an increasingly popular way to address complex topics, such as "theory of mind." However, most previous fMRI hyperscanning experiments have been limited to abstract social interactions (e.g. phone conversations). Our new method utilizes a virtual reality (VR) environment used for military training, Virtual Battlespace 2 (VBS2), to create realistic avatar-avatar interactions and cooperative tasks. To control the virtual avatar, subjects use a MRI compatible Playstation 3 game controller, modified by removing all extraneous metal components and replacing any necessary ones with 3D printed plastic models. Control of both scanners' operation is initiated by a VBS2 plugin to sync scanner time to the known time within the VR environment. Our modifications include:•Modification of game controller to be MRI compatible.•Design of VBS2 virtual environment for cooperative interactions.•Syncing two MRI machines for simultaneous recording.

Food groups and nutrient intake and risk of colorectal cancer: a hospital-based case-control study in Spain.

Science.gov (United States)

Banqué, Marta; Raidó, Blanca; Masuet, Cristina; Ramon, Josep M

2012-04-01

Although evidence supports that colorectal cancer (CRC) has an environmental etiology, the potential influence of diet appears to be one of the most important components. We studied the relation between food groups and nutrient intake and the risk of CRC. A hospital-based case-control study was conducted in Spain between 2007 and 2009. The authors matched 245 patients with incident histologically confirmed CRC by age, gender, and date of admission with 490 controls. Information about nutrient intake was gathered by using a semiquantitative frequency food questionnaire. Univariate analysis was done with individual food items. Odds ratios (ORs) for consecutive tertiles of nutrient intake were computed after allowance for sociodemographic variables and consumption of food groups. Vitamin B6 (OR: 0.26), vitamin D (OR: 0.45), vitamin E (OR: 0.42), polyunsaturated fatty acids (OR: 0.57), and fiber (OR: 0.40) were inversely associated with CRC, whereas carbohydrates (OR: 1.82) were significantly associated with CRC risk for the upper tertile. In multivariate analysis adjusting for major covariables (energy, age, and gender), vitamin D (OR:0.45), vitamin E (OR:0.36), and fiber (OR:0.46) remained associated with CRC. Data suggest that the etiology of colorectal cancer is not due to lifestyle and dietary patterns being important the effect of single nutrients.

Interactions among hydrogeomorphology, vegetation, and nutrient biogeochemistry in floodplain ecosystems

Science.gov (United States)

Noe, G.B.

2013-01-01

Hydrogeomorphic, vegetative, and biogeochemical processes interact in floodplains resulting in great complexity that provides opportunities to better understand linkages among physical and biological processes in ecosystems. Floodplains and their associated river systems are structured by four dimensional gradients of hydrogeomorphology: longitudinal, lateral, vertical, and temporal components. These four dimensions create dynamic hydrologic and geomorphologic mosaics that have a large imprint on the vegetation and nutrient biogeochemistry of floodplains. Plant physiology, population dynamics, community structure, and productivity are all very responsive to floodplain hydrogeomorphology. The strength of this relationship between vegetation and hydrogeomorphology is evident in the use of vegetation as an indicator of hydrogeomorphic processes. However, vegetation also influences hydrogeomorphology by modifying hydraulics and sediment entrainment and deposition that typically stabilize geomorphic patterns. Nitrogen and phosphorus biogeochemistry commonly influence plant productivity and community composition, although productivity is not limited by nutrient availability in all floodplains. Conversely, vegetation influences nutrient biogeochemistry through direct uptake and storage as well as production of organic matter that regulates microbial biogeochemical processes. The biogeochemistries of nitrogen and phosphorus cycling are very sensitive to spatial and temporal variation in hydrogeomorphology, in particular floodplain wetness and sedimentation. The least studied interaction is the direct effect of biogeochemistry on hydrogeomorphology, but the control of nutrient availability over organic matter decomposition and thus soil permeability and elevation is likely important. Biogeochemistry also has the more documented but indirect control of hydrogeomorphology through regulation of plant biomass. In summary, the defining characteristics of floodplain ecosystems

An Invasive Clonal Plant Benefits from Clonal Integration More than a Co-Occurring Native Plant in Nutrient-Patchy and Competitive Environments

Science.gov (United States)

You, Wenhua; Fan, Shufeng; Yu, Dan; Xie, Dong; Liu, Chunhua

2014-01-01

Many notorious invasive plants are clonal, however, little is known about the different roles of clonal integration effects between invasive and native plants. Here, we hypothesize that clonal integration affect growth, photosynthetic performance, biomass allocation and thus competitive ability of invasive and native clonal plants, and invasive clonal plants benefit from clonal integration more than co-occurring native plants in heterogeneous habitats. To test these hypotheses, two stoloniferous clonal plants, Alternanthera philoxeroides (invasive), Jussiaea repens (native) were studied in China. The apical parts of both species were grown either with or without neighboring vegetation and the basal parts without competitors were in nutrient- rich or -poor habitats, with stolon connections were either severed or kept intact. Competition significantly reduced growth and photosynthetic performance of the apical ramets in both species, but not the biomass of neighboring vegetation. Without competition, clonal integration greatly improved the growth and photosynthetic performance of both species, especially when the basal parts were in nutrient-rich habitats. When grown with neighboring vegetation, growth of J. repens and photosynthetic performance of both species were significantly enhanced by clonal integration with the basal parts in both nutrient-rich and -poor habitats, while growth and relative neighbor effect (RNE) of A. philoxeroides were greatly improved by clonal integration only when the basal parts were in nutrient-rich habitats. Moreover, clonal integration increased A. philoxeroides's biomass allocation to roots without competition, but decreased it with competition, especially when the basal ramets were in nutrient-rich sections. Effects of clonal integration on biomass allocation of J. repens was similar to that of A. philoxeroides but with less significance. These results supported our hypothesis that invasive clonal plants A. philoxeroides benefits

The Good, the Bad and the Ugly - Interacting Physical, Biogeochemical and Biolological Controls of Nutrient Cycling at Ecohydrological Interfaces

Science.gov (United States)

Krause, S.; Baranov, V. A.; Lewandowski, J.; Blaen, P. J.; Romeijn, P.

2016-12-01

The interfaces between streams, lakes and their bed sediments have for a long time been in the research focus of ecohydrologists, aquatic ecologists and biogeochemists. While over the past decades, critical understanding has been gained of the spatial patterns and temporal dynamics in nutrient cycling at sediment-freshwater interfaces, important question remain as to the actual drivers (physical, biogeochemical and biological) of the often observed hot spots and hot moments of nutrient cycling at these highly reactive systems. This study reports on a combination of laboratory manipulation, artificial stream and field experiments from reach to river network scales to investigate the interplay of physical, biogeochemical and biological drivers of interface nutrient cycling under the impact of and resilience to global environmental change. Our results indicate that biogeochemical hotspots at sediment-freshwater interfaces were controlled not only by reactant mixing ratios and residence time distributions, but strongly affected by patterns in streambed physical properties and bioavailability of organic carbon. Lab incubation experiments revealed that geology, and in particular organic matter content strongly controlled the magnitude of enhanced streambed greenhouse gas production caused by increasing water temperatures. While these findings help to improve our understanding of physical and biogeochemical controls on nutrient cycling, we only start to understand to what degree biological factors can enhance these processes even further. We found that for instance chironomid or brittle star facilitated bioturbation in has the potential to substantially enhance freshwater or marine sediment pore-water flow and respiration. We revealed that ignorance of these important biologically controls on physical exchange fluxes can lead to critical underestimation of whole system respiration and its increase under global environmental change.

Control of Saccharomyces cerevisiae catalase T gene (CTT1) expression by nutrient supply via the RAS-cyclic AMP pathway.

Science.gov (United States)

Bissinger, P H; Wieser, R; Hamilton, B; Ruis, H

1989-03-01

In Saccharomyces cerevisiae, lack of nutrients triggers a pleiotropic response characterized by accumulation of storage carbohydrates, early G1 arrest, and sporulation of a/alpha diploids. This response is thought to be mediated by RAS proteins, adenylate cyclase, and cyclic AMP (cAMP)-dependent protein kinases. This study shows that expression of the S. cerevisiae gene coding for a cytoplasmic catalase T (CTT1) is controlled by this pathway: it is regulated by the availability of nutrients. Lack of a nitrogen, sulfur, or phosphorus source causes a high-level expression of the gene. Studies with strains with mutations in the RAS-cAMP pathway and supplementation of a rca1 mutant with cAMP show that CTT1 expression is under negative control by a cAMP-dependent protein kinase and that nutrient control of CTT1 gene expression is mediated by this pathway. Strains containing a CTT1-Escherichia coli lacZ fusion gene have been used to isolate mutants with mutations in the pathway. Mutants characterized in this investigation fall into five complementation groups. Both cdc25 and ras2 alleles were identified among these mutants.

Effects of different fertilizers on growth and nutrient uptake of Lolium multiflorum grown in Cd-contaminated soils.

Science.gov (United States)

Liu, Mohan; Li, Yang; Che, Yeye; Deng, Shaojun; Xiao, Yan

2017-10-01

This study aimed to explore the effects of different fertilizers and their combinations on growth and nutrient and Cd uptake of Lolium multiflorum. Compared with control treatment, chemical fertilizer, organic manure, and their conjunctions with biofertilizer increased shoot biomass. Biofertilizers were found to cause significant reductions in shoot biomass of plants grown in organic manure-treated and control soil. Decreased soil-available N and P and shoot N and K concentrations in biofertilizer amendment treatments indicated that plant growth and nutrient absorption might be negatively affected under nutrient deficiency conditions. Elevated shoot biomasses contributed to the highest shoot Cd contents in chemical fertilizer and chemical fertilizer + biofertilizer treatments among all treatments. But the maximum translocation efficiency occurred in biofertilizer + chemical fertilizer + organic manure treatment, followed by organic manure and chemical fertilizer + organic manure treatments. Based on the results, we can conclude that the application of only the biofertilizer Bacillus subtilis should be avoided in nutrient-limited soils. Chemical fertilizer application could benefit the amount of Cd in shoots, and organic manure application and its combinations could result in the higher translocation efficiency.

Integration of optical fibers in radiative environments: Advantages and limitations

International Nuclear Information System (INIS)

Girard, S.; Ouerdane, Y.; Boukenter, A.; Marcandella, C.; Bisutti, J.; Baggio, J.; Meunier, J. P.

2011-01-01

We review the advantages and limitations for the integration of optical fibers in radiative environments. Optical fibers present numerous advantages for applications in harsh environments such as their electromagnetic immunity. This explains the increasing interest of the radiation effects community to evaluate their vulnerability for future facilities. However, it is also well-known that optical fibers suffer from a degradation of their macroscopic properties under irradiation. We illustrate the major mechanisms and parameters that govern the degradation mechanism, mainly the radiation-induced attenuation phenomena. We focus on the fiber transient radiation responses when exposed to the pulsed and mixed environment associated with the Megajoule class lasers devoted to the fusion by inertial confinement study. (authors)

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.

Modelling nutrient cycling in forest ecosystems; Modellering av naeringssyklus i skogoekosystemer

Energy Technology Data Exchange (ETDEWEB)

Kvindesland, Sheila H.S.B.

1997-12-31

Acid deposition`s threat to fresh water and forest environments became an issue in the late 1960s. Acid deposition and forest nutrient cycling then began to be researched in greater co-operation. This thesis studies nutrient cycling processes in Norway spruce forests, emphasizing the effects on soil chemical properties, soil solution chemistry and streamwater chemistry. It investigates the effects of different aged stands on nutrient cycling and sets up nutrient budgets of the base cations and nitrogen at two sites in Norway. It also selects, documents, calibrates, tests and improves nutrient cycling models for use in Norwegian forests. 84 refs., 44 figs., 46 tabs.

Soil and Nutrient Loss Following Site Preparation Burning

Science.gov (United States)

J.P. Field; E.A. Carter

2000-01-01

Sediment loss and nutrient cpncentrations in runoff were evaluated to determine the effects of site preparation burning on a recently harvested loblolly pine (Pinus taeda L.) site in east Texas. Sediment and nutrient losses prior to treatment were approximately the same from control plots and pretreatment burn plots. Nutrient analysis of runoff...

Photosynthetic capacity of tropical montane tree species in relation to leaf nutrients, successional strategy and growth temperature.

Science.gov (United States)

Dusenge, Mirindi Eric; Wallin, Göran; Gårdesten, Johanna; Niyonzima, Felix; Adolfsson, Lisa; Nsabimana, Donat; Uddling, Johan

2015-04-01

Photosynthetic capacity of tree leaves is typically positively related to nutrient content and little affected by changes in growth temperature. These relationships are, however, often poorly supported for tropical trees, for which interspecific differences may be more strongly controlled by within-leaf nutrient allocation than by absolute leaf nutrient content, and little is known regarding photosynthetic acclimation to temperature. To explore the influence of leaf nutrient status, successional strategy and growth temperature on the photosynthetic capacity of tropical trees, we collected data on photosynthetic, chemical and morphological leaf traits of ten tree species in Rwanda. Seven species were studied in a forest plantation at mid-altitude (~1,700 m), whereas six species were studied in a cooler montane rainforest at higher altitude (~2,500 m). Three species were common to both sites, and, in the montane rainforest, three pioneer species and three climax species were investigated. Across species, interspecific variation in photosynthetic capacity was not related to leaf nutrient content. Instead, this variation was related to differences in within-leaf nitrogen allocation, with a tradeoff between investments into compounds related to photosynthetic capacity (higher in pioneer species) versus light-harvesting compounds (higher in climax species). Photosynthetic capacity was significantly lower at the warmer site at 1,700 m altitude. We conclude that (1) within-leaf nutrient allocation is more important than leaf nutrient content per se in controlling interspecific variation in photosynthetic capacity among tree species in tropical Rwanda, and that (2) tropical montane rainforest species exhibit decreased photosynthetic capacity when grown in a warmer environment.

Retranslocation of foliar nutrients in evergreen tree species planted in a Mediterranean environment.

Science.gov (United States)

Fife, D N; Nambiar, E K S; Saur, E

2008-02-01

Internal nutrient recycling through retranslocation (resorption) is important for meeting the nutrient demands of new tissue production in trees. We conducted a comparative study of nutrient retranslocation from leaves of five tree species from three genera grown in plantation forests for commercial or environmental purposes in southern Australia--Acacia mearnsii De Wild., Eucalyptus globulus Labill., E. fraxinoides H. Deane & Maiden, E. grandis W. Hill ex Maiden and Pinus radiata D. Don. Significant amounts of nitrogen, phosphorus and potassium were retranslocated during three phases of leaf life. In the first phase, retranslocation occurred from young leaves beginning 6 months after leaf initiation, even when leaves were physiologically most active. In the second phase, retranslocation occurred from mature green leaves during their second year, and in the third phase, retranslocation occurred during senescence before leaf fall. Nutrient retranslocation occurred mainly in response to new shoot production. The pattern of retranslocation was remarkably similar in the leaves of all study species (and in the phyllodes of Casuarina glauca Sieber ex Spreng.), despite their diverse genetics, leaf forms and growth rates. There was no net retranslocation of calcium in any of the species. The amounts of nutrients at the start of each pre-retranslocation phase had a strong positive relationship with the amounts subsequently retranslocated, and all species fitted a common relationship. The percentage reduction in concentration or content (retranslocation efficiency) at a particular growth phase is subject to many variables, even within a species, and is therefore not a meaningful measure of interspecific variation. It is proposed that the pattern of retranslocation and its governing factors are similar among species in the absence of interspecies competition for growth and crown structure which occurs in mixed species stands.

Biogas - agriculture and environment

Energy Technology Data Exchange (ETDEWEB)

Knudsen, L; Birkmose, T [The Danish Agricultural Advisory Centre, Aarhus (Denmark)

1997-08-01

Cultivating the soil always leads to a higher loss of nutrients to the surrounding environment than the loss recorded from natural areas. Loss of nitrogen by leaching may have the effect that the set limit for nitrate of 50 mg NO{sub 3} per litre of water is exceeded in areas, where the water supply is based on ground water. Furthermore, nitrogen leaching may lead to eutrophication followed by oxygen depletion in inland waterways whereas it has hardly any significant environmental impact in freshwater areas. Ammonia volatilization followed by deposition influences nutrient-poor bio-topes like heaths, marshland etc. Increasing importance is attached to the loss of phosphorus from farmland as the discharge of sewage from urban areas and industries are reduced due to effective chemical and biological treatment plants. Environmental problems related to loss phosphorus is primarily eutrophication of freon water lakes. Nitrous oxide(N{sub 2}O), resulting from denitrification of nitrate in the soil, and the emission of methane contribute considerably to the greenhouse effect. Both nitrous oxide and the emission of methane are influenced by the volume of animal production, but no certain data on the connection and the importance are available. Loss of nutrients from farm production is primarily related to animal production. The largest environmental impact concerns the loss of nutrients in areas, where the live-stock production is very intensive in large compact areas and, where the produced amount of nutrients in animal manure and other organic manures exceed the requirements of the crops. (EG) 13 refs.

Biogas - agriculture and environment

International Nuclear Information System (INIS)

Knudsen, L.; Birkmose, T.

1997-01-01

Cultivating the soil always leads to a higher loss of nutrients to the surrounding environment than the loss recorded from natural areas. Loss of nitrogen by leaching may have the effect that the set limit for nitrate of 50 mg NO 3 per litre of water is exceeded in areas, where the water supply is based on ground water. Furthermore, nitrogen leaching may lead to eutrophication followed by oxygen depletion in inland waterways whereas it has hardly any significant environmental impact in freshwater areas. Ammonia volatilization followed by deposition influences nutrient-poor bio-topes like heaths, marshland etc. Increasing importance is attached to the loss of phosphorus from farmland as the discharge of sewage from urban areas and industries are reduced due to effective chemical and biological treatment plants. Environmental problems related to loss phosphorus is primarily eutrophication of freon water lakes. Nitrous oxide(N 2 O), resulting from denitrification of nitrate in the soil, and the emission of methane contribute considerably to the greenhouse effect. Both nitrous oxide and the emission of methane are influenced by the volume of animal production, but no certain data on the connection and the importance are available. Loss of nutrients from farm production is primarily related to animal production. The largest environmental impact concerns the loss of nutrients in areas, where the live-stock production is very intensive in large compact areas and, where the produced amount of nutrients in animal manure and other organic manures exceed the requirements of the crops. (EG) 13 refs

Presence and patterns of alkaline phosphatase activity and phosphorus cycling in natural riparian zones under changing nutrient conditions

Directory of Open Access Journals (Sweden)

Peifang Wang

2014-08-01

Full Text Available Phosphorus (P is an important limiting nutrient in aquatic ecosystems and knowledge of P cycling is fundamental for reducing harmful algae blooms and other negative effects in water. Despite their importance, the characteristics of P cycling under changing nutrient conditions in shallow lakes were poorly investigated. In this study, in situ incubation experiments were conducted in a natural riparian zone in the main diversion channel used for water transfer into Lake Taihu (Wangyu River. Variations in microbial biomass, dissolved P fractions (organic and inorganic, and alkaline phosphatase activity (bulk APA and specific APA were determined after incubation with and without the addition of P and nitrogen (N (4 total water treatments: +P, +N, +NP, and control. Experiments were conducted during two seasons (late spring and early fall to account for natural differences in nutrient levels that may occur in situ. Our results demonstrated that low levels of DRP may not necessarily indicate P limitation. Phytoplankton exhibited “serial N limitation with P stress” in May, such that chlorophyll a (Chl a increased significantly with N addition, while the limiting nutrient shifted to P in October and phytoplankton biomass increased with P addition. Phytoplankton contributed greatly to APA production and was significantly influenced by P bioavailability, yet high levels of bulk APA were also not necessarily indicative of P limitation. In contrast to phytoplankton, bacteria were less P stressed. As a consequence of enhanced utilization of dissolved reactive P (DRP and dissolved organic P (DOP, +N treatment elevated APA significantly. By contrast, APA could be repressed to low values and phytoplankton converted a large portion of DRP to DOP with P addition. But this was not consistent with bacteria APA (bact-APA in the absence or presence of abundant phytoplankton biomass. The correlation between bulk APA and DRP was good at separate sites and discrepant

[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.

Multiple nutrient stresses at intersecting Pacific Ocean biomes detected by protein biomarkers.

Science.gov (United States)

Saito, Mak A; McIlvin, Matthew R; Moran, Dawn M; Goepfert, Tyler J; DiTullio, Giacomo R; Post, Anton F; Lamborg, Carl H

2014-09-05

Marine primary productivity is strongly influenced by the scarcity of required nutrients, yet our understanding of these nutrient limitations is informed by experimental observations with sparse geographical coverage and methodological limitations. We developed a quantitative proteomic method to directly assess nutrient stress in high-light ecotypes of the abundant cyanobacterium Prochlorococcus across a meridional transect in the central Pacific Ocean. Multiple peptide biomarkers detected widespread and overlapping regions of nutritional stress for nitrogen and phosphorus in the North Pacific Subtropical Gyre and iron in the equatorial Pacific. Quantitative protein analyses demonstrated simultaneous stress for these nutrients at biome interfaces. This application of proteomic biomarkers to diagnose ocean metabolism demonstrated Prochlorococcus actively and simultaneously deploying multiple biochemical strategies for low-nutrient conditions in the oceans. Copyright © 2014, American Association for the Advancement of Science.

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

Visual operations control in administrative environments

Energy Technology Data Exchange (ETDEWEB)

Carson, M.L.; Levine, L.O.

1995-03-01

When asked what comes to mind when they think of ``controlling work`` in the office, people may respond with ``overbearing boss,`` ``no autonomy,`` or ``Theory X management.`` The idea of controlling work in white collar or administrative environments can have a negative connotation. However, office life is often chaotic and miserable precisely because the work processes are out of control, and managers must spend their time looking over people`s shoulders and fighting fires. While management styles and structures vary, the need for control of work processes does not. Workers in many environments are being reorganized into self-managed work teams. These teams are expected to manage their own work through increased autonomy and empowerment. However, even empowered work teams must manage their work processes because of process variation. The amount of incoming jobs vary with both expected (seasonal) and unexpected demand. The mixture of job types vary over time, changing the need for certain skills or knowledge. And illness and turnover affect the availability of workers with needed skills and knowledge. Clearly, there is still a need to control work, whether the authority for controlling work is vested in one person or many. Visual control concepts provide simple, inexpensive, and flexible mechanisms for managing processes in work teams and continuous improvement administrative environments.

Effects of nutrients and zooplankton on the phytoplankton community structure in Marudu Bay

Science.gov (United States)

Tan, Kar Soon; Ransangan, Julian

2017-07-01

Current study was carried out to provide a better understanding on spatial and temporal variations in the phytoplankton community structure in Marudu Bay, an important nursery ground for fishery resources within the Tun Mustapha Marine Park and Coral Triangle Initiative, and their relationship with environmental variables. Samplings were conducted monthly from April 2014 to April 2015 in Marudu Bay, Malaysia. Water samples were collected for nutrients analysis, zooplankton and phytoplankton counting. Moreover, the in situ environmental parameters were also examined. The field study showed a total of forty seven phytoplankton genera, representative of 33 families were identified. The nutrient concentrations in Marudu Bay was low (mesotrophic) throughout the year, where the phytoplankton community was often dominated by Chaetoceros spp. and Bacteriastrum spp. In general, increase in nitrate concentration triggered the bloom of centric diatom, Chaetoceros spp. and Bacteriastrum spp. in Marudu Bay. However, the bloom of these phytoplankton taxa did not occur in the presence of high ammonia concentration. In addition, high abundance of zooplankton also a limiting factor of the phytoplankton blooms particularly at end of southwest monsoon. High silica concentration promoted the growth of pennate diatoms, Proboscia spp. and Thallassionema spp., but the depletion of silica quickly terminated the bloom. Interestingly, our study showed that Chaetoceros spp., tolerated silica depletion condition, but the average cell size of this taxon reduced significantly. In summary, the phytoplankton community structure in mesotrophic environment is more sensitive to the changes in zooplankton abundance, nutrient concentration and its ratio than that in nutrient rich environments. This study also recommends that bivalve farming at industrial scale is not recommended in Marudu Bay because it potentially depletes the primary productivity hence jeopardizing the availability of live food for

Determining the potential productivity of food crops in controlled environments

Science.gov (United States)

Bugbee, Bruce

1992-01-01

The quest to determine the maximum potential productivity of food crops is greatly benefitted by crop growth models. Many models have been developed to analyze and predict crop growth in the field, but it is difficult to predict biological responses to stress conditions. Crop growth models for the optimal environments of a Controlled Environment Life Support System (CELSS) can be highly predictive. This paper discusses the application of a crop growth model to CELSS; the model is used to evaluate factors limiting growth. The model separately evaluates the following four physiological processes: absorption of PPF by photosynthetic tissue, carbon fixation (photosynthesis), carbon use (respiration), and carbon partitioning (harvest index). These constituent processes determine potentially achievable productivity. An analysis of each process suggests that low harvest index is the factor most limiting to yield. PPF absorption by plant canopies and respiration efficiency are also of major importance. Research concerning productivity in a CELSS should emphasize: (1) the development of gas exchange techniques to continuously monitor plant growth rates and (2) environmental techniques to reduce plant height in communities.

Feedback interactions between trace metal nutrients and phytoplankton in the ocean

Directory of Open Access Journals (Sweden)

William eSunda

2012-06-01

Full Text Available In addition to control by major nutrient elements (nitrogen, phosphorus, and silicon the productivity and species composition of marine phytoplankton communities are affected by a number of trace metal nutrients (iron, zinc, cobalt, manganese, copper, and cadmium. Of these, iron exerts the greatest limiting influence on carbon fixation rates and has the greatest effect on algal species diversity. It also plays an important role in limiting di-nitrogen (N2 fixation rates, and thus exerts an important influence on ocean inventories of biologically available fixed nitrogen. Because of these effects, iron is thought to play a key role in controlling the biological cycles of carbon and nitrogen in the ocean, including the biological transfer of carbon to the deep sea, the so-called biological CO2 pump, which helps regulate atmospheric CO2 levels and CO2-linked global warming. Other trace metal nutrients (zinc, cobalt, copper, and manganese have a lesser effect on productivity; but may exert an important influence on the species composition of algal communities because of large differences in metal requirements among algal species. The interactions between trace metals and ocean plankton are reciprocal: not only do the metals affect the plankton, but the plankton regulate the distributions, chemical speciation, and cycling of these metals through cellular uptake and regeneration processes, downward flux of biogenic particles, cellular release of organic chelators, and mediation of redox reactions. This two way interaction has influenced not only the biology and chemistry of the modern ocean, but has had a profound influence on biogeochemistry of the ocean and earth system as a whole, and on the evolution marine and terrestrial biology over geologic history.

TFTR movable limiter instrumentation and controls

International Nuclear Information System (INIS)

Frankenberg, J.; Collins, D.; Kaufmann, D.; Mamoun, A.

1983-01-01

The TFTR movable limiter is a single poloidal limiter located within one 18 /SUP o/ segment of the vacuum vessel. It consists of three (3) interconnected inconel backing plates covered with titanium carbide coated graphite tiles. The backing plates are positioned by three independent screw drive actuators. Cooling water is fed through the horizontal port cover to tubes brazed onto the backs of the backing plates. Thermocouples monitor the limiter temperature. (1) and more fully described in refs. (1) and (2). The positioning actuators are driven by independently controlled DC servo motors, controlled either locally or from CICADA. Drive motor shaft position is monitored by chain driven encoders and potentiometers. Limiter blade position can be varied to suit any plasma within the operating range. CICADA is programmed to keep the limiter stroke within safe operating limits. A microprocessor duplicates the CICADA protective function allowing limiter operation without CICADA. The potentiometer signal is sent to an analog computer, which safeguards the limiter against failure of the encoders or the micro-processor. Cooling water flows through the limiter in 3 separate paths, one for each blade. The flow rate and temperature rise through each loop are measured accurately to allow CICADA to calculate the heat into each blade. The water system is also interlocked and alarmed to prevent dumping of water into the vacuum vessel

Profile control simulations and experiments on TCV: a controller test environment and results using a model-based predictive controller

Science.gov (United States)

Maljaars, E.; Felici, F.; Blanken, T. C.; Galperti, C.; Sauter, O.; de Baar, M. R.; Carpanese, F.; Goodman, T. P.; Kim, D.; Kim, S. H.; Kong, M.; Mavkov, B.; Merle, A.; Moret, J. M.; Nouailletas, R.; Scheffer, M.; Teplukhina, A. A.; Vu, N. M. T.; The EUROfusion MST1-team; The TCV-team

2017-12-01

The successful performance of a model predictive profile controller is demonstrated in simulations and experiments on the TCV tokamak, employing a profile controller test environment. Stable high-performance tokamak operation in hybrid and advanced plasma scenarios requires control over the safety factor profile (q-profile) and kinetic plasma parameters such as the plasma beta. This demands to establish reliable profile control routines in presently operational tokamaks. We present a model predictive profile controller that controls the q-profile and plasma beta using power requests to two clusters of gyrotrons and the plasma current request. The performance of the controller is analyzed in both simulation and TCV L-mode discharges where successful tracking of the estimated inverse q-profile as well as plasma beta is demonstrated under uncertain plasma conditions and the presence of disturbances. The controller exploits the knowledge of the time-varying actuator limits in the actuator input calculation itself such that fast transitions between targets are achieved without overshoot. A software environment is employed to prepare and test this and three other profile controllers in parallel in simulations and experiments on TCV. This set of tools includes the rapid plasma transport simulator RAPTOR and various algorithms to reconstruct the plasma equilibrium and plasma profiles by merging the available measurements with model-based predictions. In this work the estimated q-profile is merely based on RAPTOR model predictions due to the absence of internal current density measurements in TCV. These results encourage to further exploit model predictive profile control in experiments on TCV and other (future) tokamaks.

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

Healthy Snacks: Using Nutrient Profiling to Evaluate the Nutrient-Density of Common Snacks in the United States.

Science.gov (United States)

Hess, Julie M; Slavin, Joanne L

2017-09-01

To quantify and compare the nutrient-density of commonly consumed snacks using two nutrient-density measures, Nutrient Rich Foods Indices 9.3 (NRF 9.3) and 15.3 (NRF 15.3). Identify commonly consumed categories of snacks and individual snack foods, calculate NRF 9.3 and 15.3 scores, rank snacks by category and by individual food based on nutrient density, compare and contrast scores generated by the two NRF Indices. NRF 9.3 and 15.3 scores. Averages and standard deviations of nutrient-density scores for each snack category. Vegetables and coffee/tea received the highest category scores on both indices. Cakes/cookies/pastries and sweets had the lowest category scores. NRF 9.3 scores for individual snacks ranged from -46 (soda) to 524 (coffee). NRF 15.3 scores ranged from -45 (soda) to 736 (coffee). If added to food labels, NRF scores could help consumers identify more nutritious choices. The differences between NRF 9.3 and 15.3 scores generated for the same foods and the limitations of these indices highlight the need for careful consideration of which nutrient-density measure to include on food labels as well as consumer education. © 2017 Institute of Food Technologists®.

Integrated control algorithms for plant environment in greenhouse

Science.gov (United States)

Zhang, Kanyu; Deng, Lujuan; Gong, Youmin; Wang, Shengxue

2003-09-01

In this paper a survey of plant environment control in artificial greenhouse was put forward for discussing the future development. Firstly, plant environment control started with the closed loop control of air temperature in greenhouse. With the emergence of higher property computer, the adaptive control algorithm and system identification were integrated into the control system. As adaptation control is more depending on observation of variables by sensors and yet many variables are unobservable or difficult to observe, especially for observation of crop growth status, so model-based control algorithm were developed. In order to evade modeling difficulty, one method is predigesting the models and the other method is utilizing fuzzy logic and neural network technology that realize the models by the black box and gray box theory. Studies on control method of plant environment in greenhouse by means of expert system (ES) and artificial intelligence (AI) have been initiated and developed. Nowadays, the research of greenhouse environment control focus on energy saving, optimal economic profit, enviornment protection and continualy develop.

Decoherence control in different environments

International Nuclear Information System (INIS)

Paavola, J.; Maniscalco, S.

2010-01-01

We investigate two techniques for controlling decoherence, focusing on the crucial role played by the environmental spectrum. We show how environments with different spectra lead to very different dynamical behaviors. Our study clearly proves that such differences must be taken into account when designing decoherence control schemes. The two techniques we consider are reservoir engineering and quantum Zeno control. We focus on a quantum harmonic oscillator initially prepared in a nonclassical state and derive analytically its non-Markovian dynamics in the presence of different bosonic thermal environments. On the one hand, we show how, by modifying the spectrum of the environment, it is possible to prolong or reduce the life of a Schroedinger cat state. On the other hand, we study the effect of nonselective energy measurements on the degradation of quantumness of initial Fock states. In this latter case, we see that the crossover between quantum Zeno and anti-Zeno effects, discussed by Maniscalco et al. [Phys. Rev. Lett. 97, 130402 (2006)], is highly sensitive to the details of the spectrum. In particular, for certain types of spectra, even very small variations of the system frequency may cause a measurement-induced acceleration of decoherence rather than its inhibition.

Plasma nutrient status of patients with Alzheimer's disease: Systematic review and meta-analysis.

Science.gov (United States)

Lopes da Silva, Sofia; Vellas, Bruno; Elemans, Saskia; Luchsinger, José; Kamphuis, Patrick; Yaffe, Kristine; Sijben, John; Groenendijk, Martine; Stijnen, Theo

2014-07-01

Alzheimer disease (AD) patients are at risk of nutritional insufficiencies because of physiological and psychological factors. Nutritional compounds are postulated to play a role in the pathophysiological processes that are affected in AD. We here provide the first systematic review and meta-analysis that compares plasma levels of micronutrients and fatty acids in AD patients to those in cognitively intact elderly controls. A secondary objective was to explore the presence of different plasma nutrient levels between AD and control populations that did not differ in measures of protein/energy nourishment. We screened literature published after 1990 in the Cochrane Central Register of Controlled Trials, Medline, and Embase electronic databases using Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines for AD patients, controls, micronutrient, vitamins, and fatty acids, resulting in 3397 publications, of which 80 met all inclusion criteria. Status of protein/energy malnutrition was assessed by body mass index, mini nutritional assessment score, or plasma albumin. Meta-analysis, with correction for differences in mean age between AD patients and controls, was performed when more than five publications were retrieved for a specific nutrient. We identified five or more studies for folate, vitamin A, vitamin B12, vitamin C, vitamin D, vitamin E, copper, iron, and zinc but fewer than five studies for vitamins B1 and B6, long-chain omega-3 fatty acids, calcium, magnesium, manganese, and selenium (the results of the individual publications are discussed). Meta-analysis showed significantly lower plasma levels of folate and vitamin A, vitamin B12, vitamin C, and vitamin E (P vitamin D (P = .075) were found in AD patients. No significant differences were observed for plasma levels of copper and iron. A meta-analysis that was limited to studies reporting no differences in protein/energy malnourishment between AD and control populations yielded

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

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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

Hyperspectral remote sensing analysis of short rotation woody crops grown with controlled nutrient and irrigation treatments

Science.gov (United States)

Jungho Im; John R. Jensen; Mark Coleman; Eric. Nelson

2009-01-01

Hyperspectral remote sensing research was conducted to document the biophysical and biochemical characteristics of controlled forest plots subjected to various nutrient and irrigation treatments. The experimental plots were located on the Savannah River Site near Aiken, SC. AISA hyperspectral imagery were analysed using three approaches, including: (1) normalized...

Nutrient-induced stimulation of protein synthesis in mouse skeletal muscle is limited by the mTORC1 repressor REDD1.

Science.gov (United States)

Gordon, Bradley S; Williamson, David L; Lang, Charles H; Jefferson, Leonard S; Kimball, Scot R

2015-04-01

In skeletal muscle, the nutrient-induced stimulation of protein synthesis requires signaling through the mechanistic target of rapamycin complex 1 (mTORC1). Expression of the repressor of mTORC1 signaling, regulated in development and DNA damage 1 (REDD1), is elevated in muscle during various atrophic conditions and diminished under hypertrophic conditions. The question arises as to what extent REDD1 limits the nutrient-induced stimulation of protein synthesis. The objective was to examine the role of REDD1 in limiting the response of muscle protein synthesis and mTORC1 signaling to a nutrient stimulus. Wild type REDD1 gene (REDD1(+/+)) and disruption in the REDD1 gene (REDD1(-/-)) mice were feed deprived for 16 h and randomized to remain feed deprived or refed for 15 or 60 min. The tibialis anterior was then removed for analysis of protein synthesis and mTORC1 signaling. In feed-deprived mice, protein synthesis and mTORC1 signaling were significantly lower in REDD1(+/+) than in REDD1(-/-) mice. Thirty minutes after the start of refeeding, protein synthesis in REDD1(+/+) mice was stimulated by 28%, reaching a value similar to that observed in feed-deprived REDD1(-/-) mice, and was accompanied by increased phosphorylation of mTOR (Ser2448), p70S6K1 (Thr389), and 4E-BP1 (Ser65) by 81%, 167%, and 207%, respectively. In refed REDD1(-/-) mice, phosphorylation of mTOR (Ser2448), p70S6K1 (Thr389), and 4E-BP1 (Ser65) were significantly augmented above the values observed in refed REDD1(+/+) mice by 258%, 405%, and 401%, respectively, although protein synthesis was not coordinately increased. Seventy-five minutes after refeeding, REDD1 expression in REDD1(+/+) mice was reduced (∼15% of feed-deprived REDD1(+/+) values), and protein synthesis and mTORC1 signaling were not different between refed REDD1(+/+) mice and REDD1(-/-) mice. The results show that REDD1 expression limits protein synthesis in mouse skeletal muscle by inhibiting mTORC1 signaling during periods of feed

Growth of the coccolithophore Emiliania huxleyi in light- and nutrient-limited batch reactors: relevance for the BIOSOPE deep ecological niche of coccolithophores

Science.gov (United States)

Perrin, Laura; Probert, Ian; Langer, Gerald; Aloisi, Giovanni

2016-11-01

Coccolithophores are unicellular calcifying marine algae that play an important role in the oceanic carbon cycle via their cellular processes of photosynthesis (a CO2 sink) and calcification (a CO2 source). In contrast to the well-studied, surface-water coccolithophore blooms visible from satellites, the lower photic zone is a poorly known but potentially important ecological niche for coccolithophores in terms of primary production and carbon export to the deep ocean. In this study, the physiological responses of an Emiliania huxleyi strain to conditions simulating the deep niche in the oligotrophic gyres along the BIOSOPE transect in the South Pacific Gyre were investigated. We carried out batch culture experiments with an E. huxleyi strain isolated from the BIOSOPE transect, reproducing the in situ conditions of light and nutrient (nitrate and phosphate) limitation. By simulating coccolithophore growth using an internal stores (Droop) model, we were able to constrain fundamental physiological parameters for this E. huxleyi strain. We show that simple batch experiments, in conjunction with physiological modelling, can provide reliable estimates of fundamental physiological parameters for E. huxleyi that are usually obtained experimentally in more time-consuming and costly chemostat experiments. The combination of culture experiments, physiological modelling and in situ data from the BIOSOPE cruise show that E. huxleyi growth in the deep BIOSOPE niche is limited by availability of light and nitrate. This study contributes more widely to the understanding of E. huxleyi physiology and behaviour in a low-light and oligotrophic environment of the ocean.

Nutrient amendment does not increase mineralisation of sequestered carbon during incubation of a nitrogen limited mangrove soil

KAUST Repository

Keuskamp, Joost A.; Schmitt, Heike; Laanbroek, Hendrikus J.; Verhoeven, Jos T.A.; Hefting, Mariet M.

2013-01-01

Mangrove forests are sites of intense carbon and nutrient cycling, which result in soil carbon sequestration on a global scale. Currently, mangrove forests receive increasing quantities of exogenous nutrients due to coastal development. The present

DOOCS environment for FPGA-based cavity control system and control algorithms development

International Nuclear Information System (INIS)

Pucyk, P.; Koprek, W.; Kaleta, P.; Szewinski, J.; Pozniak, K.T.; Czarski, T.; Romaniuk, R.S.

2005-01-01

The paper describes the concept and realization of the DOOCS control software for FPGAbased TESLA cavity controller and simulator (SIMCON). It bases on universal software components, created for laboratory purposes and used in MATLAB based control environment. These modules have been recently adapted to the DOOCS environment to ensure a unified software to hardware communication model. The presented solution can be also used as a general platform for control algorithms development. The proposed interfaces between MATLAB and DOOCS modules allow to check the developed algorithm in the operation environment before implementation in the FPGA. As the examples two systems have been presented. (orig.)

An operating environment for control systems on transputer networks

NARCIS (Netherlands)

Tillema, H.G.; Schoute, Albert L.; Wijbrans, K.C.J.; Wijbrans, K.C.J.

1991-01-01

The article describes an operating environment for control systems. The environment contains the basic layers of a distributed operating system. The design of this operating environment is based on the requirements demanded by controllers which can be found in complex control systems. Due to the

Methane productivity and nutrient recovery from manure

Energy Technology Data Exchange (ETDEWEB)

Moeller, H.B.

2003-07-01

The efficient recovery of energy and improvements in the handling of nutrients from manure have attracted increased research focus during recent decades. Anaerobic digestion is a key process in any strategy for the recovery of energy, while slurry separation is an important component in an improved nutrient-handling strategy. This thesis is divided into two parts: the first deals mainly with nutrient recovery strategies and the second examines biological degradation processes, including controlled anaerobic digestion. (au)

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

Infection control practice in countries with limited resources

Directory of Open Access Journals (Sweden)

Alp Emine

2011-10-01

Full Text Available Abstract Nosocomial infections and their control are a world-wide challenge. The prevalence of nosocomial infections is generally higher in developing countries with limited resources than industrialized countries. In this paper we aimed to further explain the differences with regard to infection control challenges between Turkey, a country with "limited" resources, and the Netherlands, a country with "reasonable" resources. Infrastructure of hospitals, low compliance of hand hygiene, understaffing, overcrowding, heavy workload, misuse of personal protective equipments, late establishment of infection control programme are major problems in limited-resources countries. These problems cause high infection rates and spread of multi-drug resistant pathogens. To improve the control and prevention of infections in countries with limited resources, a multi-facet approach is needed.

Parental Low Self-Control, Family Environments, and Juvenile Delinquency.

Science.gov (United States)

Meldrum, Ryan C; Connolly, George M; Flexon, Jamie; Guerette, Rob T

2016-10-01

Research consistently finds that low self-control is significantly correlated with delinquency. Only recently, however, have researchers started to examine associations between parental low self-control, family environments, and child antisocial behavior. Adding to this emerging area of research, the current study examines associations between parental low self-control, aspects of the family environment, and officially recoded juvenile delinquency among a sample (N = 101) of juveniles processed through a juvenile justice assessment facility located in the Southeastern United States. Furthermore, it considers whether aspects of family environments, particularly family cohesion, family conflict, and parental efficacy, mediate the influence of parental low self-control on delinquency. The results of a series of analyses indicate that parental low self-control is correlated with various aspects of family environments and juvenile delinquency, and that the association between parental low self-control and juvenile delinquency is mediated by family environments. Supplementary analyses also suggest that the association between parental low self-control and the family environment may be reciprocal. © The Author(s) 2015.

Predator-driven nutrient recycling in California stream ecosystems.

Directory of Open Access Journals (Sweden)

Robin G Munshaw

Full Text Available Nutrient recycling by consumers in streams can influence ecosystem nutrient availability and the assemblage and growth of photoautotrophs. Stream fishes can play a large role in nutrient recycling, but contributions by other vertebrates to overall recycling rates remain poorly studied. In tributaries of the Pacific Northwest, coastal giant salamanders (Dicamptodon tenebrosus occur at high densities alongside steelhead trout (Oncorhynchus mykiss and are top aquatic predators. We surveyed the density and body size distributions of D. tenebrosus and O. mykiss in a California tributary stream, combined with a field study to determine mass-specific excretion rates of ammonium (N and total dissolved phosphorus (P for D. tenebrosus. We estimated O. mykiss excretion rates (N, P by bioenergetics using field-collected data on the nutrient composition of O. mykiss diets from the same system. Despite lower abundance, D. tenebrosus biomass was 2.5 times higher than O. mykiss. Mass-specific excretion summed over 170 m of stream revealed that O. mykiss recycle 1.7 times more N, and 1.2 times more P than D. tenebrosus, and had a higher N:P ratio (8.7 than that of D. tenebrosus (6.0, or the two species combined (7.5. Through simulated trade-offs in biomass, we estimate that shifts from salamander biomass toward fish biomass have the potential to ease nutrient limitation in forested tributary streams. These results suggest that natural and anthropogenic heterogeneity in the relative abundance of these vertebrates and variation in the uptake rates across river networks can affect broad-scale patterns of nutrient limitation.

Food for thought: how nutrients regulate root system architecture.

Science.gov (United States)

Shahzad, Zaigham; Amtmann, Anna

2017-10-01

The spatial arrangement of the plant root system (root system architecture, RSA) is very sensitive to edaphic and endogenous signals that report on the nutrient status of soil and plant. Signalling pathways underpinning RSA responses to individual nutrients, particularly nitrate and phosphate, have been unravelled. Researchers have now started to investigate interactive effects between two or more nutrients on RSA. Several proteins enabling crosstalk between signalling pathways have recently been identified. RSA is potentially an important trait for sustainable and/or marginal agriculture. It is generally assumed that RSA responses are adaptive and optimise nutrient uptake in a given environment, but hard evidence for this paradigm is still sparse. Here we summarize recent advances made in these areas of research. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Closed-Cycle Nutrient Supply For Hydroponics

Science.gov (United States)

Schwartzkopf, Steven H.

1991-01-01

Hydroponic system controls composition and feed rate of nutrient solution and recovers and recycles excess solution. Uses air pressure on bladders to transfer aqueous nutrient solution. Measures and adjusts composition of solution before it goes to hydroponic chamber. Eventually returns excess solution to one of tanks. Designed to operate in microgravity, also adaptable to hydroponic plant-growing systems on Earth.

Assessment of nitrogen and phosphorus flows in agricultural and urban systems in a small island under limited data availability

NARCIS (Netherlands)

Firmansyah, I.; Spiller, M.; Ruijter, De F.J.; Carsjens, G.J.; Zeeman, G.

2017-01-01

Nitrogen (N) and phosphorus (P) are two essential macronutrients required in agricultural production. The
major share of this production relies on chemical fertilizer that requires energy and relies on limited resources
(P). Since these nutrients are lost to the environment, there is a need

The role and control of sludge age in biological nutrient removal activated sludge systems.

Science.gov (United States)

Ekama, G A

2010-01-01

The sludge age is the most fundamental and important parameter in the design, operation and control of biological nutrient removal (BNR) activated sludge (AS) systems. Generally, the better the effluent and waste sludge quality required from the system, the longer the sludge age, the larger the biological reactor and the more wastewater characteristics need to be known. Controlling the reactor concentration does not control sludge age, only the mass of sludge in the system. When nitrification is a requirement, sludge age control becomes a requirement and the secondary settling tanks can no longer serve the dual purpose of clarifier and waste activated sludge thickeners. The easiest and most practical way to control sludge age is with hydraulic control by wasting a defined proportion of the reactor volume daily. In AS plants with reactor concentration control, nitrification fails first. With hydraulic control of sludge age, nitrification will not fail, rather the plant fails by shedding solids over the secondary settling tank effluent weirs.

Investigating genotype specific response in photosynthetic behavior under drought stress and nitrogen limitation in Brassica rapa.

Science.gov (United States)

Pleban, J. R.; Mackay, D. S.; Ewers, B. E.; Weinig, C.; Aston, T.

2015-12-01

Challenges in terrestrial ecosystem modeling include characterizing the impact of stress on vegetation and the heterogeneous behavior of different species within the environment. In an effort to address these challenges the impacts of drought and nutrient limitation on the CO2 assimilation of multiple genotypes of Brassica rapa was investigated using the Farquhar Model (FM) of photosynthesis following a Bayesian parameterization and updating scheme. Leaf gas exchange and chlorophyll fluorescence measurements from an unstressed group (well-watered/well-fertilized) and two stressed groups (drought/well-fertilized and well-watered/nutrient limited) were used to estimate FM model parameters. Unstressed individuals were used to initialize Bayesian parameter estimation. Posterior mean estimates yielded a close fit with data as observed assimilation (An) closely matched predicted (Ap) with mean standard error for all individuals ranging from 0.8 to 3.1 μmol CO2 m-2 s-1. Posterior parameter distributions of the unstressed individuals were combined and fit to distributions to establish species level Bayesian priors of FM parameters for testing stress responses. Species level distributions of unstressed group identified mean maximum rates of carboxylation standardized to 25° (Vcmax25) as 101.8 μmol m-2 s-1 (± 29.0) and mean maximum rates of electron transport standardized to 25° (Jmax25) as 319.7 μmol m-2 s-1 (± 64.4). These updated priors were used to test the response of drought and nutrient limitations on assimilation. In the well-watered/nutrient limited group a decrease of 28.0 μmol m-2 s-1 was observed in mean estimate of Vcmax25, a decrease of 27.9 μmol m-2 s-1 in Jmax25 and a decrease in quantum yield from 0.40 mol photon/mol e- in unstressed individuals to 0.14 in the nutrient limited group. In the drought/well-fertilized group a decrease was also observed in Vcmax25 and Jmax25. The genotype specific unstressed and stressed responses were then used to

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.

Prospective evidence for independent nitrogen and phosphorus limitation of grasshopper (Chorthippus curtipennis) growth in a tallgrass prairie.

Science.gov (United States)

Rode, Madison; Lemoine, Nathan P; Smith, Melinda D

2017-01-01

Insect herbivores play a pivotal role in regulating plant production and community composition, and their role in terrestrial ecosystems is partly determined by their feeding behavior and performance among plants of differing nutritional quality. Historically, nitrogen (N) has been considered the primary limiting nutrient of herbivorous insects, but N is only one of many potential nutrients important to insect performance. Of these nutrients, phosphorus (P) is perhaps the most important because somatic growth depends upon P-rich ribosomal RNA. Yet relatively few studies have assessed the strength of P-limitation for terrestrial insects and even fewer have simultaneously manipulated both N and P to assess the relative strengths of N- and P-limitation. Here, we tested for potential N and P limitation, as well as N:P co-limitation, on Chorthippis curtipennis (Orthoptera, Acrididae), an abundant member of arthropod communities of central US prairies. Our results demonstrate weak evidence for both N and P limitation of C. curtipennis growth rates in laboratory feeding assays. Importantly, P-limitation was just as strong as N-limitation, but we found no evidence for NP co-limitation in our study. Furthermore, nutrient limitation was not apparent in field studies, suggesting that insect growth rates may be predominately controlled by other factors, including temperature and predation. Our results suggest that P should be jointly considered, along with N, as a primary determinant of herbivore feeding behavior under both current and future climate conditions.

Water and nutrient productivity in melon crop by fertigation under subsurface drip irrigation and mulching in contrasting soils

Directory of Open Access Journals (Sweden)

Rodrigo Otávio Câmara Monteiro

2014-01-01

Full Text Available Cropping intensification and technical, economic and environmental issues require efficient application of production factors to maintain the soil productive capacity and produce good quality fruits and vegetables. The production factors, water and NPK nutrients, are the most frequent limiting factors to higher melon yields. The objective of the present study was to identify the influence of subsurface drip irrigation and mulching in a protected environment on the water and NPK nutrients productivity in melon cropped in two soil types: sandy loam and clay. The melon crop cultivated under environmental conditions with underground drip irrigation at 0.20m depth, with mulching on sandy loam soil increased water and N, P2O5 and K use efficiency.

Controlling open quantum systems: tools, achievements, and limitations

International Nuclear Information System (INIS)

Koch, Christiane P

2016-01-01

The advent of quantum devices, which exploit the two essential elements of quantum physics, coherence and entanglement, has sparked renewed interest in the control of open quantum systems. Successful implementations face the challenge of preserving relevant nonclassical features at the level of device operation. A major obstacle is decoherence, which is caused by interaction with the environment. Optimal control theory is a tool that can be used to identify control strategies in the presence of decoherence. Here we review recent advances in optimal control methodology that allow typical tasks in device operation for open quantum systems to be tackled and discuss examples of relaxation-optimized dynamics. Optimal control theory is also a useful tool to exploit the environment for control. We discuss examples and point out possible future extensions. (topical review)

Modeling adaptation of wetland plants under changing environments

Science.gov (United States)

Muneepeerakul, R.; Muneepeerakul, C. P.

2010-12-01

An evolutionary-game-theoretic approach is used to study the changes in traits of wetland plants in response to environmental changes, e.g., altered patterns of rainfall and nutrients. Here, a wetland is considered as a complex adaptive system where plants can adapt their strategies and influence one another. The system is subject to stochastic rainfall, which controls the dynamics of water level, soil moisture, and alternation between aerobic and anaerobic conditions in soil. Based on our previous work, a plant unit is characterized by three traits, namely biomass nitrogen content, specific leaf area, and allocation to rhizome. These traits control the basic functions of plants such as assimilation, respiration, and nutrient uptake, while affecting their environment through litter chemistry, root oxygenation, and thus soil microbial dynamics. The outcome of this evolutionary game, i.e., the best-performing plant traits against the backdrop of these interactions and feedbacks, is analyzed and its implications on important roles of wetlands in supporting our sustainability such as carbon sequestration in biosphere, nutrient cycling, and repository of biodiversity are discussed.

Biological Nutrient Removal in Compact Biofilm Systems

NARCIS (Netherlands)

Bassin, J.P.

2012-01-01

The removal of nutrients such as nitrogen and phosphorus from both domestic and industrial wastewaters is imperative since they potentially harm the environment. One of the main consequences of excessive availability of nitrogen and phosphorus in aquatic ecosystems (freshwater, marine and estuarine)

Generating news media interest in tobacco control; challenges in an advanced policy environment.

Science.gov (United States)

MacKenzie, Ross; Chapman, Simon

2012-08-01

To determine the efficacy of using media releases for tobacco control advocacy in Australia's advanced policy environment. Between February and August 2010, news releases that summarised either newly published but unpublicized research findings, or local developments in tobacco control, were sent to NSW media outlets. Reports arising from the releases were tracked using commercial services Media Monitors and Factiva, as well as Google and Google News. Other tobacco control related news items during the same period were also tracked and recorded. Twenty-one news releases generated 93 news items across all news media, with a quarter of these related to a story of porcine haemoglobin in cigarette filters. By comparison, 'live' policy issues (especially plain packaging and a significant tobacco tax increase) covered in this period attracted 1,033 news stories in the Australian media. Press releases describing recently published, but underpublicized research were issued in weeks where no major competing tobacco control news occurred. Results of this project indicate that in environments with advanced tobacco policy, media opportunities related to tobacco control advocacy are limited, as many objectives have been achieved. The media can still play a key advocacy role in such environments, and advocates need to be particularly vigilant for opportunities that do arise. The paper also highlights the increasingly important role of internet-based media, including opportunities presented by social media for tobacco control.

Maintaining adequate nutrient supply - Principles, decision-support tools, and best management practices [Chapter 6

Science.gov (United States)

Robert B. Harrison; Douglas A. Maguire; Deborah Page-Dumroese

2011-01-01

Maintaining adequate nutrient supply to maintain or enhance tree vigor and forest growth requires conservation of topsoil and soil organic matter. Sometimes nutrient amendments are also required to supplement inherent nutrient-pool limitations or replenish nutrients removed in harvested material. The goal is to maintain the productive potential of the soil and, when...

Soil an-d nutrient loss following site preparation burning

Science.gov (United States)

E.A. Carter; J.P. Field; K.W. Farrish

2000-01-01

Sediment loss and nutrient cpncentrations in runoff were evaluated to determine the effects of site preparation burning on a recently harvested loblolly pine (Pinur taeda L.) site in east Texas. Sediment and nutrient losses prior to treatment were approximately the same from control plots and pretreatment burn plots. Nutrient analysis of runoff samples indicated that...

The influence of dietary and whole-body nutrient content on the excretion of a vertebrate consumer.

Directory of Open Access Journals (Sweden)

Christopher M Dalton

Full Text Available In many contexts, nutrient excretion by consumers can impact ecosystems by altering the availability of limiting nutrients. Variation in nutrient excretion can be predicted by mass balance models, most of which are premised on two key ideas: (1 consumers maintain fixed whole-body nutrient content (i.e., %N and %P, so-called fixed homeostasis; (2 if dietary nutrients are not matched to whole-body nutrients, excesses of any nutrient are released as excretion to maintain fixed homeostasis. Mass balance models thus predict that consumer excretion should be positively correlated with diet nutrients and negatively correlated with whole-body nutrients. Recent meta-analyses and field studies, however, have often failed to find these expected patterns, potentially because of a confounding influence-flexibility in whole-body nutrient content with diet quality (flexible homeostasis. Here, we explore the impact of flexible homeostasis on nutrient excretion by comparing the N and P excretion of four genetically diverged Trinidadian guppy (Poecilia reticulata populations when reared on diets of variable P content. As predicted by mass balance, P excretion increased on the high-P diet, but, contrary to the notion of fixed homeostasis, guppy whole-body %P also increased on the high-P diet. While there was no overall correlation between excretion nutrients and whole-body nutrients, when the effect of diet on both whole-body and excretion nutrients was included, we detected the expected negative correlation between whole-body N:P and excretion N:P. This last result suggests that mass balance can predict excretion rates within species, but only if dietary effects on whole-body nutrient content are controlled. Flexible homeostasis can obscure patterns predicted by mass balance, creating an imperative to accurately capture an organism's diet quality in predicting its excretion rate.

Seasonal nutrient dynamics and biomass quality of giant reed (Arundo donax L. and miscanthus (Miscanthus x giganteus Greef et Deuter as energy crops

Directory of Open Access Journals (Sweden)

Nicoletta Nassi o Di Nasso

2011-08-01

Full Text Available The importance of energy crops in displacing fossil fuels within the energy sector in Europe is growing. Among energy crops, the use of perennial rhizomatous grasses (PRGs seems promising owing to their high productivity and their nutrient recycling that occurs during senescence. In particular, nutrient requirements and biomass quality have a fundamental relevance to biomass systems efficiency. The objective of our study was to compare giant reed (Arundo donax L. and miscanthus (Miscanthus × giganteus Greef et Deuter in terms of nutrient requirements and cellulose, hemicelluloses and lignin content. This aim was to identify, in the Mediterranean environment, the optimal harvest time that may combine, beside a high biomass yield, high nutrient use efficiency and a good biomass quality for second generation biofuel production. The research was carried out in 2009, in San Piero a Grado, Pisa (Central Italy; latitude 43°41’ N, longitude 10°21’ E, on seven-year-old crops in a loam soil characterised by good water availability. Maximum above-ground nutrient contents were generally found in summer. Subsequently, a decrease was recorded; this suggested a nutrient remobilisation from above-ground biomass to rhizomes. In addition, miscanthus showed the highest N, P, and K use efficiency, probably related to its higher yield and its C4 pathway. Regarding biomass quality, stable values of cellulose (38%, hemicelluloses (25% and lignin (8% were reported from July onwards in both crops. Hence, these components appear not to be discriminative parameters in the choice of the harvest time in the Mediterranean environment. In conclusion, our results highlighted that, in our environment, a broad harvest period (from late autumn to winter seems suitable for these PRGs. However, further research is required to evaluate the role of rhizomes in nutrient storage and supply during the growing season, as well as ecological and productive performances in marginal

Improving crop nutrient efficiency through root architecture modifications.

Science.gov (United States)

Li, Xinxin; Zeng, Rensen; Liao, Hong

2016-03-01

Improving crop nutrient efficiency becomes an essential consideration for environmentally friendly and sustainable agriculture. Plant growth and development is dependent on 17 essential nutrient elements, among them, nitrogen (N) and phosphorus (P) are the two most important mineral nutrients. Hence it is not surprising that low N and/or low P availability in soils severely constrains crop growth and productivity, and thereby have become high priority targets for improving nutrient efficiency in crops. Root exploration largely determines the ability of plants to acquire mineral nutrients from soils. Therefore, root architecture, the 3-dimensional configuration of the plant's root system in the soil, is of great importance for improving crop nutrient efficiency. Furthermore, the symbiotic associations between host plants and arbuscular mycorrhiza fungi/rhizobial bacteria, are additional important strategies to enhance nutrient acquisition. In this review, we summarize the recent advances in the current understanding of crop species control of root architecture alterations in response to nutrient availability and root/microbe symbioses, through gene or QTL regulation, which results in enhanced nutrient acquisition. © 2015 Institute of Botany, Chinese Academy of Sciences.

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.

Central nervous control of nutrient availability and utilization.

NARCIS (Netherlands)

Steffens, A.B; Benthem, L; van der Heide, D.; Huisman, E.A.; Kanis, E.; Osse, J.W.M.; Verstegen, M.W.A.

1999-01-01

In resting animals (rats) fed ad libitum on carbohydrate-rich food, nutrient deposition in the reserves (glycogen in liver and fat in adipocytes) is in equilibrium with utilization. In this situation, metabolic needs are covered for 50% energy by glucose and 50% energy by free fatty acids (FFA). The

A critical assessment of the ecological assumptions underpinning compensatory mitigation of salmon-derived nutrients

Science.gov (United States)

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

2015-01-01

We critically evaluate some of the key ecological assumptions underpinning the use of nutrient replacement as a means of recovering salmon populations and a range of other organisms thought to be linked to productive salmon runs. These assumptions include: (1) nutrient mitigation mimics the ecological roles of salmon, (2) mitigation is needed to replace salmon-derived nutrients and stimulate primary and invertebrate production in streams, and (3) food resources in rearing habitats limit populations of salmon and resident fishes. First, we call into question assumption one because an array of evidence points to the multi-faceted role played by spawning salmon, including disturbance via redd-building, nutrient recycling by live fish, and consumption by terrestrial consumers. Second, we show that assumption two may require qualification based upon a more complete understanding of nutrient cycling and productivity in streams. Third, we evaluate the empirical evidence supporting food limitation of fish populations and conclude it has been only weakly tested. On the basis of this assessment, we urge caution in the application of nutrient mitigation as a management tool. Although applications of nutrients and other materials intended to mitigate for lost or diminished runs of Pacific salmon may trigger ecological responses within treated ecosystems, contributions of these activities toward actual mitigation may be limited.

Nutrient and chlorophyll a anomaly in red-tide periods of 2003-2008 in Sishili Bay, China

Science.gov (United States)

Hao, Yanju; Tang, Danling; Yu, Long; Xing, Qianguo

2011-05-01

Sishili Bay is the most important aquiculture and tourism area for the city of Yantai, China; however, red tides occurred frequently and have caused huge economic losses in this bay in recent years. To gain a better understanding of the local ecological environments in the bay, we conducted this research between 2003 and 2008 to analyze variations in nutrients and chlorophyll (chl- a) during high frequency red tide period (May to September). The results show that the chl- a concentration increased from 2.70 in 2003 to 7.26 mg/m3 in 2008, while the concentration of total inorganic nitrogen (TIN) and silicate (SiO3-Si) increased lineally from 5.18 and 1.45 μmol/L in 2003 to 18.57 and 9.52 μmol/L in 2008, respectively, and the annual phosphate (PO4-P) varied between 0.15 and 0.46 μmol/L. Special attention was given to a red tide in August 2007 occurred when water temperature was high and nutrient concentrations increased sharply because of a heavy rainfall. Overall, the results show the P limitation in Sishili Bay, and reveal that red tides were caused by eutrophication from terrestrial inputs and local warm weather, particularly during rainy periods. Therefore, to control red tide, greater efforts should be made to reduce sewage discharges into Sishili Bay, particularly during rainfall seasons.

Advances and challenges for nutrient management in china in the 21st century.

Science.gov (United States)

Sims, J T; Ma, L; Oenema, O; Dou, Z; Zhang, F S

2013-07-01

Managing agricultural nutrients to provide a safe and secure food supply while protecting the environment remains one of the great challenges for the 21st century. The fourth International Nutrient Management Symposium (INMS), held in 2011 at the University of Delaware, addressed these issues via presentations, panel sessions, and field tours focused on latest technologies and policies available to increase nutrient use efficiency. Participants from the United States, Europe, Canada, and China discussed global trends and challenges, balancing food security and the environment in countries with struggling and emerging economics, nutrient management and transport at the catchment scale, new technologies for managing fertilizer and manure nutrients, and adaptive nutrient management practices for farm to watershed scales. A particular area of interest at the fourth INMS was nutrient management progress and challenges in China over the past 40 years. China's food security challenges and rapidly growing economy have led to major advances in agricultural production systems but also created severe nutrient pollution problems. This special collection of papers from the fourth INMS gives an overview of the remarkable progress China has made in nutrient management and highlights major challenges and changes in agri-environmental policies and practices needed today. Lessons learned in China are of value to both developing and developed countries facing the common task of providing adequate food for an expanding world population, while protecting air and water quality and restoring damaged ecosystems. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Limiting our impact on the environment

CERN Multimedia

2012-01-01

CERN’s fourth safety objective for 2012 concerns the reduction of the environmental impact of noise and energy consumption associated with CERN's activities.   In order to continue to reduce the impact of noise on our neighbours, the HSE Unit is coordinating measures to reduce noise in the environment at all the LHC and SPS points, and on the Meyrin and Prévessin sites. If you are aware of a high-intensity noise that could disturb those living and working close to our sites, you can contact the HSE Unit. And most important of all, please take this potential nuisance into account when you're planning new projects. The HSE Unit is there to help you. The other aspect of our environmental target for the year is to optimise CERN's energy consumption. We can achieve this by limiting the energy consumption of facilities right from the design stage - from small components to large installations - and by using renewable energies even on a sma...

Effects of the duration and inorganic nitrogen composition of a nutrient-rich patch on soil exploration by the roots of Lolium perenne in a heterogeneous environment.

Science.gov (United States)

Nakamura, Ryoji; Kachi, N; Suzuki, J-I

2010-05-01

We investigated the growth of and soil exploration by Lolium perenne under a heterogeneous environment before its roots reached a nutrient-rich patch. Temporal changes in the distribution of inorganic nitrogen, i.e., NO(3)(-)-N and NH(4)(+)-N, in the heterogeneous environment during the experimental period were also examined. The results showed that roots randomly explored soil, irrespective of the patchy distribution of inorganic nitrogen and differences in the chemical composition of inorganic nitrogen distribution between heterogeneous and homogeneous environments. We have also elucidated the potential effects of patch duration and inorganic nitrogen distribution on soil exploration by roots and thus on plant growth.

Impact of the river Liffey discharge on nutrient and chlorophyll concentrations in the Liffey estuary and Dublin Bay (Irish Sea)

Science.gov (United States)

O'Higgins, T. G.; Wilson, J. G.

2005-08-01

Temperature, salinity, nutrients (total oxidised nitrogen (TON), ammonium (NH 4) and orthophosphate (PO 4)) and chlorophyll a were monitored in the Liffey estuary and Dublin Bay from June 2000 to June 2003. Four groups of sites were defined comprising the upper estuary (Gp. I), the outer estuary (Gp. III) with a small set (Gp. II) of sites between Groups I and III heavily influenced by the sewage treatment works outflow, and the Bay proper (Gp. IV). Riverine inputs of TON and PO 4 were calculated at an average of 826 t N y -1 and 31 t P y -1, respectively, and were largely controlled by flow rate. The sewage treatment works were identified as a major source of PO 4 and NH 4 to the system. Mixing in the upper estuary of nutrient limited saline waters with hypernutrified river water regularly (i.e. annually) produced relatively high concentrations of chlorophyll a (>10 mg chl a m -3), and also sporadic blooms with extremely high chlorophyll a values (max. 121.6 mg chl a m -3). These latter phytoplankton blooms occurred in high salinity waters and were due to mixing of nutrient limited saline waters and nutrient rich river waters. The mean annual flux of phytoplankton carbon from the river Liffey was calculated at 23.5 t C y -1, of which half was accumulated or remineralised in the estuary and did not enter the Bay. In the Bay proper (Gp. IV) summer nutrient concentrations dropped below detection limits, and chlorophyll a concentrations followed the classic pattern with a spring bloom maximum of 5.5 mg chl a m -3. This pattern in nutrients and chlorophyll a came from the advection of waters into the Bay from an offshore source. Overall while there was considerable evidence for eutrophication in the estuary, the bay itself showed little biological response to nutrient loading.

An Investigation of Anaerobic Processes in Fuel/Natural Seawater Environments

Science.gov (United States)

2012-02-08

separated esters and glycerin. Biodiesel contains no sulfur. In the United States the term "biodiesel" is standardized as fatty acid methyl ester ( FAME ...crude oil remaining. Biodiesel is produced from vegetable oils by converting the triglyceride oils to methyl (or ethyl) esters with a process known...water from the environment. Microbial growth in seawater can be limited by nutrients, including carbon. Biodiesel methyl esters are quite sparingly

Advances and Challenges for Nutrient Management in China in the 21st Century

NARCIS (Netherlands)

Sims, J.T.; Ma, L.; Oenema, O.; Dou, Z.; Zhang, F.S.

2013-01-01

Managing agricultural nutrients to provide a safe and secure food supply while protecting the environment remains one of the great challenges for the 21st century. The fourth International Nutrient Management Symposium (INMS), held in 2011 at the University of Delaware, addressed these issues via

Seasonal variability in the persistence of dissolved environmental DNA (eDNA in a marine system: The role of microbial nutrient limitation.

Directory of Open Access Journals (Sweden)

Ian Salter

Full Text Available Environmental DNA (eDNA can be defined as the DNA pool recovered from an environmental sample that includes both extracellular and intracellular DNA. There has been a significant increase in the number of recent studies that have demonstrated the possibility to detect macroorganisms using eDNA. Despite the enormous potential of eDNA to serve as a biomonitoring and conservation tool in aquatic systems, there remain some important limitations concerning its application. One significant factor is the variable persistence of eDNA over natural environmental gradients, which imposes a critical constraint on the temporal and spatial scales of species detection. In the present study, a radiotracer bioassay approach was used to quantify the kinetic parameters of dissolved eDNA (d-eDNA, a component of extracellular DNA, over an annual cycle in the coastal Northwest Mediterranean. Significant seasonal variability in the biological uptake and turnover of d-eDNA was observed, the latter ranging from several hours to over one month. Maximum uptake rates of d-eDNA occurred in summer during a period of intense phosphate limitation (turnover <5 hrs. Corresponding increases in bacterial production and uptake of adenosine triphosphate (ATP demonstrated the microbial utilization of d-eDNA as an organic phosphorus substrate. Higher temperatures during summer may amplify this effect through a general enhancement of microbial metabolism. A partial least squares regression (PLSR model was able to reproduce the seasonal cycle in d-eDNA persistence and explained 60% of the variance in the observations. Rapid phosphate turnover and low concentrations of bioavailable phosphate, both indicative of phosphate limitation, were the most important parameters in the model. Abiotic factors such as pH, salinity and oxygen exerted minimal influence. The present study demonstrates significant seasonal variability in the persistence of d-eDNA in a natural marine environment that can

Simulation of three-phase induction motor drives using indirect field oriented control in PSIM environment

Science.gov (United States)

Aziri, Hasif; Patakor, Fizatul Aini; Sulaiman, Marizan; Salleh, Zulhisyam

2017-09-01

This paper presents the simulation of three-phase induction motor drives using Indirect Field Oriented Control (IFOC) in PSIM environment. The asynchronous machine is well known about natural limitations fact of highly nonlinearity and complexity of motor model. In order to resolve these problems, the IFOC is applied to control the instantaneous electrical quantities such as torque and flux component. As FOC is controlling the stator current that represented by a vector, the torque component is aligned with d coordinate while the flux component is aligned with q coordinate. There are five levels of the incremental system are gradually built up to verify and testing the software module in the system. Indeed, all of system build levels are verified and successfully tested in PSIM environment. Moreover, the corresponding system of five build levels are simulated in PSIM environment which is user-friendly for simulation studies in order to explore the performance of speed responses based on IFOC algorithm for three-phase induction motor drives.

Limitation of multi-elemental fingerprinting of wheat grains: Effect of cultivar, sowing date, and nutrient management

DEFF Research Database (Denmark)

Suarez-Tapia, Alfonso; Kucheryavskiy, Sergey V.; Christensen, Bent Tolstrup

2017-01-01

Multi-element fingerprinting demonstrates some potential for tracing the origin of agricultural products but not for discriminating among crop cultivars and nutrient management (source, rate). With principal component analysis (PCA) and univariate statistics, we examined 19 elements in grains from...... two winter wheat cultivars (Hereford, Mariboss) grown with different rates of animal manure (AM) or mineral fertilisers (NPK) in a long-term field experiment and two sowing dates (early, timely). Nitrogen, Cd and Mn related to NPK, and Mo and Na to AM. Barium, Fe, and P reflected nutrient rate......; these elements increased with nutrient rate regardless of source. Unmanured grains were enriched in Cu. Mariboss was characterized by higher concentrations of Sr, Ba and Sc compared to Hereford with Sr in grain as the main separator. Univariate statistics showed higher concentrations of N, P, Mg, Ba, Cu, Mo...

Removal of nutrient limitations in forest gaps enhances growth rate and resistance to cavitation in subtropical canopy tree species differing in shade tolerance.

Science.gov (United States)

Villagra, Mariana; Campanello, Paula I; Montti, Lia; Goldstein, Guillermo

2013-03-01

A 4-year fertilization experiment with nitrogen (N) and phosphorus (P) was carried out in natural gaps of a subtropical forest in northeastern Argentina. Saplings of six dominant canopy species differing in shade tolerance were grown in five control and five N + P fertilized gaps. Hydraulic architectural traits such as wood density, the leaf area to sapwood area ratio (LA : SA), vulnerability to cavitation (P50) and specific and leaf-specific hydraulic conductivity were measured, as well as the relative growth rate, specific leaf area (SLA) and percentage of leaf damage by insect herbivores. Plant growth rates and resistance to drought-induced embolisms increased when nutrient limitations were removed. On average, the P50 of control plants was -1.1 MPa, while the P50 of fertilized plants was -1.6 MPa. Wood density and LA : SA decreased with N + P additions. A trade-off between vulnerability to cavitation and efficiency of water transport was not observed. The relative growth rate was positively related to the total leaf surface area per plant and negatively related to LA : SA, while P50 was positively related to SLA across species and treatments. Plants with higher growth rates and higher total leaf area in fertilized plots were able to avoid hydraulic dysfunction by becoming less vulnerable to cavitation (more negative P50). Two high-light-requiring species exhibited relatively low growth rates due to heavy herbivore damage. Contrary to expectations, shade-tolerant plants with relatively high resistance to hydraulic dysfunction and reduced herbivory damage were able to grow faster. These results suggest that during the initial phase of sapling establishment in gaps, species that were less vulnerable to cavitation and exhibited reduced herbivory damage had faster realized growth rates than less shade-tolerant species with higher potential growth rates. Finally, functional relationships between hydraulic traits and growth rate across species and treatments

Maternal nutrient restriction during pregnancy impairs an endothelium-derived hyperpolarizing factor-like pathway in sheep fetal coronary arteries.

Science.gov (United States)

Shukla, Praveen; Ghatta, Srinivas; Dubey, Nidhi; Lemley, Caleb O; Johnson, Mary Lynn; Modgil, Amit; Vonnahme, Kimberly; Caton, Joel S; Reynolds, Lawrence P; Sun, Chengwen; O'Rourke, Stephen T

2014-07-15

The mechanisms underlying developmental programming are poorly understood but may be associated with adaptations by the fetus in response to changes in the maternal environment during pregnancy. We hypothesized that maternal nutrient restriction during pregnancy alters vasodilator responses in fetal coronary arteries. Pregnant ewes were fed a control [100% U.S. National Research Council (NRC)] or nutrient-restricted (60% NRC) diet from days 50 to 130 of gestation (term = 145 days); fetal tissues were collected at day 130. In coronary arteries isolated from control fetal lambs, relaxation to bradykinin was unaffected by nitro-l-arginine (NLA). Iberiotoxin or contraction with KCl abolished the NLA-resistant response to bradykinin. In fetal coronary arteries from nutrient-restricted ewes, relaxation to bradykinin was fully suppressed by NLA. Large-conductance, calcium-activated potassium channel (BKCa) currents did not differ in coronary smooth muscle cells from control and nutrient-restricted animals. The BKCa openers, BMS 191011 and NS1619, and 14,15-epoxyeicosatrienoic acid [a putative endothelium-derived hyperpolarizing factor (EDHF)] each caused fetal coronary artery relaxation and BKCa current activation that was unaffected by maternal nutrient restriction. Expression of BKCa-channel subunits did not differ in fetal coronary arteries from control or undernourished ewes. The results indicate that maternal undernutrition during pregnancy results in loss of the EDHF-like pathway in fetal coronary arteries in response to bradykinin, an effect that cannot be explained by a decreased number or activity of BKCa channels or by decreased sensitivity to mediators that activate BKCa channels in vascular smooth muscle cells. Under these conditions, bradykinin-induced relaxation is completely dependent on nitric oxide, which may represent an adaptive response to compensate for the absence of the EDHF-like pathway. Copyright © 2014 the American Physiological Society.

Use of hydroponics culture to assess nutrient supply by treated wastewater

Energy Technology Data Exchange (ETDEWEB)

Adrover, M.; Moya, G.; Vadell, J.

2009-07-01

The use of treated wastewater for irrigation is increasing, especially in those areas where water resources are limited. Treated wastewaters contain nutrients that are useful for plant growth and help to reduce fertilizers needs. Nutrient content of these waters depends on the treatment system. (Author)

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

Yield Gap, Indigenous Nutrient Supply and Nutrient Use Efficiency for Maize in China

OpenAIRE

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 m...

Nutrient-enhanced decomposition of plant biomass in a freshwater wetland

Science.gov (United States)

Bodker, James E.; Turner, Robert Eugene; Tweel, Andrew; Schulz, Christopher; Swarzenski, Christopher M.

2015-01-01

We studied soil decomposition in a Panicum hemitomon (Schultes)-dominated freshwater marsh located in southeastern Louisiana that was unambiguously changed by secondarily-treated municipal wastewater effluent. We used four approaches to evaluate how belowground biomass decomposition rates vary under different nutrient regimes in this marsh. The results of laboratory experiments demonstrated how nutrient enrichment enhanced the loss of soil or plant organic matter by 50%, and increased gas production. An experiment demonstrated that nitrogen, not phosphorus, limited decomposition. Cellulose decomposition at the field site was higher in the flowfield of the introduced secondarily treated sewage water, and the quality of the substrate (% N or % P) was directly related to the decomposition rates. We therefore rejected the null hypothesis that nutrient enrichment had no effect on the decomposition rates of these organic soils. In response to nutrient enrichment, plants respond through biomechanical or structural adaptations that alter the labile characteristics of plant tissue. These adaptations eventually change litter type and quality (where the marsh survives) as the % N content of plant tissue rises and is followed by even higher decomposition rates of the litter produced, creating a positive feedback loop. Marsh fragmentation will increase as a result. The assumptions and conditions underlying the use of unconstrained wastewater flow within natural wetlands, rather than controlled treatment within the confines of constructed wetlands, are revealed in the loss of previously sequestered carbon, habitat, public use, and other societal benefits.

Controlling percolation with limited resources

Science.gov (United States)

Schröder, Malte; Araújo, Nuno A. M.; Sornette, Didier; Nagler, Jan

2017-12-01

Connectivity, or the lack thereof, is crucial for the function of many man-made systems, from financial and economic networks over epidemic spreading in social networks to technical infrastructure. Often, connections are deliberately established or removed to induce, maintain, or destroy global connectivity. Thus, there has been a great interest in understanding how to control percolation, the transition to large-scale connectivity. Previous work, however, studied control strategies assuming unlimited resources. Here, we depart from this unrealistic assumption and consider the effect of limited resources on the effectiveness of control. We show that, even for scarce resources, percolation can be controlled with an efficient intervention strategy. We derive such an efficient strategy and study its implications, revealing a discontinuous transition as an unintended side effect of optimal control.

Nutrient removal by apple, pear and cherry nursery trees

OpenAIRE

Giovambattista Sorrenti; Maurizio Quartieri; Silvia Salvi; Moreno Toselli

2017-01-01

Given that nursery is a peculiar environment, the amount of nutrients removed by nursery trees represents a fundamental acquisition to optimise fertilisation strategies, with economic and environmental implications. In this context, we determined nutrient removal by apple, pear and cherry nursery trees at the end of the nursery growing cycle. We randomly removed 5 leafless apple (Golden Delicious/EMLA M9; density of 30,000 trees ha–1), pear (Santa Maria/Adams; density of 30,000 trees ha–1) an...

Use of hydroponics culture to assess nutrient supply by treated wastewater.

Science.gov (United States)

Adrover, Maria; Moyà, Gabriel; Vadell, Jaume

2013-09-30

The use of treated wastewater for irrigation is increasing, especially in those areas where water resources are limited. Treated wastewaters contain nutrients that are useful for plant growth and help to reduce fertilizers needs. Nutrient content of these waters depends on the treatment system. Nutrient supply by a treated wastewater from a conventional treatment plant (CWW) and a lagooned wastewater from the campus of the University of Balearic Islands (LWW) was tested in an experiment in hydroponics conditions. Half-strength Hoagland nutrient solution (HNS) was used as a control. Barley (Hordeum vulgare L.) seedlings were grown in 4 L containers filled with the three types of water. Four weeks after planting, barley was harvested and root and shoot biomass was measured. N, P, K, Ca, Mg, Na and Fe contents were determined in both tissues and heavy metal concentrations were analysed in shoots. N, P and K concentrations were lower in LWW than in CWW, while HNS had the highest nutrient concentration. Dry weight barley production was reduced in CWW and LWW treatments to 49% and 17%, respectively, comparing to HNS. However, to a lesser extent, reduction was found in shoot and root N content. Treated wastewater increased Na content in shoots and roots of barley and Ca and Cr content in shoots. However, heavy metals content was lower than toxic levels in all the cases. Although treated wastewater is an interesting water resource, additional fertilization is needed to maintain a high productivity in barley seedlings. Copyright © 2013 Elsevier Ltd. All rights reserved.

Associative visual learning by tethered bees in a controlled visual environment.

Science.gov (United States)

Buatois, Alexis; Pichot, Cécile; Schultheiss, Patrick; Sandoz, Jean-Christophe; Lazzari, Claudio R; Chittka, Lars; Avarguès-Weber, Aurore; Giurfa, Martin

2017-10-10

Free-flying honeybees exhibit remarkable cognitive capacities but the neural underpinnings of these capacities cannot be studied in flying insects. Conversely, immobilized bees are accessible to neurobiological investigation but display poor visual learning. To overcome this limitation, we aimed at establishing a controlled visual environment in which tethered bees walking on a spherical treadmill learn to discriminate visual stimuli video projected in front of them. Freely flying bees trained to walk into a miniature Y-maze displaying these stimuli in a dark environment learned the visual discrimination efficiently when one of them (CS+) was paired with sucrose and the other with quinine solution (CS-). Adapting this discrimination to the treadmill paradigm with a tethered, walking bee was successful as bees exhibited robust discrimination and preferred the CS+ to the CS- after training. As learning was better in the maze, movement freedom, active vision and behavioral context might be important for visual learning. The nature of the punishment associated with the CS- also affects learning as quinine and distilled water enhanced the proportion of learners. Thus, visual learning is amenable to a controlled environment in which tethered bees learn visual stimuli, a result that is important for future neurobiological studies in virtual reality.

Bluetooth helper environment

Science.gov (United States)

Zhang, Junbiao

2001-10-01

Handheld devices are gaining great popularity and becoming a common commodity on the market primarily due to their small sizes and mobile nature. However, these devices are all limited in capabilities, especially in terms of screen display, processing power, storage space and network access. Some of these limitations, such as the small screen sizes, are inherently difficult to improve given the usage model of these devices. In this paper, we propose a framework in which small handheld devices can use their environment, the devices around them, to expand their limited capabilities. Such an environment can be deployed in the office, at home for user convenience or in a public access area as a revenue generating service. A handheld device interacts with the helper environment through several essential steps including device discovery, service query, request transfer and remote control. In order to ensure the proper operation of such an environment, the framework provides essential system components for admission control, resource allocation, task scheduling and device coordination. We refer to such a framework as the device helper environment and discuss its system architecture and usage scenarios in this paper.

International lighting in controlled environments workshop: Proceedings

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-12-31

Lighting is a central and critical aspect of control in environmental research for plant research and is gaining recognition as a significant factor to control carefully for animal and human research. Thus this workshop was convened to reevaluate the technology that is available today and to work toward developing guidelines for the most effective use of lighting in controlled environments with emphasis on lighting for plants but also to initiate interest in the development of improved guidelines for human and animal research. There are a number of established guidelines for lighting in human and animal environments. Development of new lighting guidelines is necessary for three reasons: (1) recent scientific discoveries show that in addition to supporting the sensation of vision, light has profound nonvisual biological and behavioral effects in both animals and humans; (2) federal regulations (EPACT 1992) are requiring all indoor environments to become more energy efficient with a specific emphasis on energy conservation in lighting; (3) lighting engineers and manufacturers have developed a wealth of new light sources and lighting products that can be applied in animal and human environments. The workshop was aimed at bringing together plant scientists and physical scientists to interact in the discussions. It involved participation of biological scientists involved in studying mechanisms of light reactions and those involved in utilizing lighting for production of plants and maintenance of animals in controlled environments. It included participation of physical scientists from universities and government involved in research as well as those from industry involved in producing lamps and in construction of controlled growth facilities. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

Gustatory and metabolic perception of nutrient stress in Drosophila.

Science.gov (United States)

Linford, Nancy J; Ro, Jennifer; Chung, Brian Y; Pletcher, Scott D

2015-02-24

Sleep loss is an adaptive response to nutrient deprivation that alters behavior to maximize the chances of feeding before imminent death. Organisms must maintain systems for detecting the quality of the food source to resume healthy levels of sleep when the stress is alleviated. We determined that gustatory perception of sweetness is both necessary and sufficient to suppress starvation-induced sleep loss when animals encounter nutrient-poor food sources. We further find that blocking specific dopaminergic neurons phenocopies the absence of gustatory stimulation, suggesting a specific role for these neurons in transducing taste information to sleep centers in the brain. Finally, we show that gustatory perception is required for survival, specifically in a low nutrient environment. Overall, these results demonstrate an important role for gustatory perception when environmental food availability approaches zero and illustrate the interplay between sensory and metabolic perception of nutrient availability in regulating behavioral state.

Taking a low glycemic index multi-nutrient supplement as breakfast improves glycemic control in patients with type 2 diabetes mellitus: a randomized controlled trial.

Science.gov (United States)

Li, Di; Zhang, Peiwen; Guo, Honghui; Ling, Wenhua

2014-12-10

Dietary therapy is the mainstay of treatment for diabetes. This study examined the effect of a low glycemic index (GI) multi-nutrient supplement, consumed in place of breakfast, on glycemic control in patients with type 2 diabetes mellitus (T2DM). A total of 71 participants were randomized at a 2:1 ratio into either a breakfast replacement group or a normal breakfast group for a 12-week interventional study. The primary outcome measure was change in hemoglobin A1c (HbA1c). Nutrition status and somatometry were studied as secondary outcomes. The breakfast replacement group displayed a -0.2% absolute reduction in HbA1c (95% CI (confidence interval), -0.38% to -0.07%, p = 0.004), while the HbA1c of the control group increased 0.3% (95% CI, 0.1% to 0.5%, p = 0.005). The baseline Mini Nutritional Assessment score for both groups was 26.0 and no significant changes occurred following intervention. However, there was a statistically significant difference in body mass index between the treatment and control groups (p = 0.032) due to the weight gain in the control group (increased 0.5 kg, 95% CI was 0.2 to 0.9, p = 0.007). These data suggest that breakfast replacement with a low GI multi-nutrient supplement can improve glycemic and weight control in T2DM.

Development of an automated flow injection analysis system for determination of phosphate in nutrient solutions.

Science.gov (United States)

Karadağ, Sevinç; Görüşük, Emine M; Çetinkaya, Ebru; Deveci, Seda; Dönmez, Koray B; Uncuoğlu, Emre; Doğu, Mustafa

2018-01-25

A fully automated flow injection analysis (FIA) system was developed for determination of phosphate ion in nutrient solutions. This newly developed FIA system is a portable, rapid and sensitive measuring instrument that allows on-line analysis and monitoring of phosphate ion concentration in nutrient solutions. The molybdenum blue method, which is widely used in FIA phosphate analysis, was adapted to the developed FIA system. The method is based on the formation of ammonium Mo(VI) ion by reaction of ammonium molybdate with the phosphate ion present in the medium. The Mo(VI) ion then reacts with ascorbic acid and is reduced to the spectrometrically measurable Mo(V) ion. New software specific for flow analysis was developed in the LabVIEW development environment to control all the components of the FIA system. The important factors affecting the analytical signal were identified as reagent flow rate, injection volume and post-injection flow path length, and they were optimized using Box-Behnken experimental design and response surface methodology. The optimum point for the maximum analytical signal was calculated as 0.50 mL min -1 reagent flow rate, 100 µL sample injection volume and 60 cm post-injection flow path length. The proposed FIA system had a sampling frequency of 100 samples per hour over a linear working range of 3-100 mg L -1 (R 2  = 0.9995). The relative standard deviation (RSD) was 1.09% and the limit of detection (LOD) was 0.34 mg L -1 . Various nutrient solutions from a tomato-growing hydroponic greenhouse were analyzed with the developed FIA system and the results were found to be in good agreement with vanadomolybdate chemical method findings. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Model development for nutrient loading estimates from paddy rice fields in Korea.

Science.gov (United States)

Jeon, Ji-Hong; Yoon, Chun G; Ham, Jong-Hwa; Jung, Kwang-Wook

2004-01-01

A field experiment was performed to evaluate water and nutrient balances in paddy rice culture operations during 2001-2002. The water balance analysis indicated that about half (50-60%) of the total outflow was lost by surface drainage, with the remainder occurring by evapotranspiration (490-530 mm). The surface drainage from paddy fields was mainly caused by rainfall and forced-drainage, and in particular, the runoff during early rice culture periods depends more on the forced-drainage due to fertilization practices. Most of the total phosphorus (T-P) inflow was supplied by fertilization at transplanting, while the total nitrogen (T-N) inflow was supplied by the three fertilizations, precipitation. and from the upper paddy field, which comprised 13-33% of the total inflow. Although most of the nutrient outflow was attributed to plant uptake. nutrient loss by surface drainage was substantial, comprising 20% for T-N and 10% for T-P. Water and nutrient balances indicate that reduction of surface drainage from paddy rice fields is imperative for nonpoint source pollution control. The simplified computer model, PADDIMOD, was developed to simulate water and nutrient (T-N and T-P) behavior in the paddy rice field. The model predicts daily ponded water depth, surface drainage, and nutrient concentrations. It was formulated with a few equations and simplified assumptions, but its application and a model fitness test indicated that the simulation results reasonably matched the observed data. It is a simple and convenient planning model that could be used to evaluate BMPs of paddy rice fields alone or in combination with other complex watershed models. Application of the PADDIMOD to other paddy rice fields with different agricultural environments might require further calibration and validation.

Nutrient dietary patterns and the risk of colorectal cancer: a case-control study from Italy.

Science.gov (United States)

Bravi, Francesca; Edefonti, Valeria; Bosetti, Cristina; Talamini, Renato; Montella, Maurizio; Giacosa, Attilio; Franceschi, Silvia; Negri, Eva; Ferraroni, Monica; La Vecchia, Carlo; Decarli, Adriano

2010-11-01

The role of diet on colorectal cancer has been considered in terms of single foods and nutrients, but less frequently in terms of dietary patterns. Data were derived from an Italian case-control study, including 1,225 subjects with cancer of the colon, 728 subjects with rectal cancer, and 4,154 hospital controls. We identified dietary patterns on a selected set of nutrients through principal component factor analysis. Odds ratios (OR) and 95% confidence intervals for both cancers were estimated using unconditional multiple logistic regression. We identified 5 major dietary patterns. Direct associations were observed between the Starch-rich pattern and both cancer of the colon (OR = 1.68) and of the rectum (OR = 1.74). Inverse relationships were found between the Vitamins and fiber pattern and rectal cancer (OR = 0.61), between the Unsaturated fats (animal source) and the Unsaturated fats (vegetable source) and cancer of the colon (OR = 0.80 and OR = 0.79, respectively). No other significant association was found. The Starch-rich pattern is potentially an unfavorable indicator of risk for both colon and rectal cancer, whereas the Vitamins and fiber pattern is associated with a reduced risk of rectal cancer and the Unsaturated fats patterns with a reduced risk of colon cancer.

Potential of Waste Water Use for Jatropha Cultivation in Arid Environments

Directory of Open Access Journals (Sweden)

Folkard Asch

2012-12-01

Full Text Available Water is crucial for socio-economic development and healthy ecosystems. With the actual population growth and in view of future water scarcity, development calls for improved sectorial allocation of groundwater and surface water for domestic, agricultural and industrial use. Instead of intensifying the pressure on water resources, leading to conflicts among users and excessive pressure on the environment, sewage effluents, after pre-treatment, provide an alternative nutrient-rich water source for agriculture in the vicinity of cities. Water scarcity often occurs in arid and semiarid regions affected by droughts and large climate variability and where the choice of crop to be grown is limited by the environmental factors. Jatropha has been introduced as a potential renewable energy resource since it is claimed to be drought resistant and can be grown on marginal sites. Sewage effluents provide a source for water and nutrients for cultivating jatropha, a combined plant production/effluent treatment system. Nevertheless, use of sewage effluents for irrigation in arid climates carries the risk of salinization. Thus, potential irrigation with sewage effluents needs to consider both the water requirement of the crop and those needed for controlling salinity build-up in the top soil. Using data from a case study in Southern Morocco, irrigation requirements were calculated using CROPWAT 8.0. We present here crop evapotranspiration during the growing period, required irrigation, the resulting nutrient input and the related risk of salinization from the irrigation of jatropha with sewage effluent.

The Impact of Nitrogen Limitation and Mycorrhizal Symbiosis on Aspen Tree Growth and Development

Energy Technology Data Exchange (ETDEWEB)

Tran, Bich Thi Ngoc [Univ. of Alabama, Huntsville, AL (United States)

2014-08-18

Nitrogen deficiency is the most common and widespread nutritional deficiency affecting plants worldwide. Ectromycorrhizal symbiosis involves the beneficial interaction of plants with soil fungi and plays a critical role in nutrient cycling, including the uptake of nitrogen from the environment. The main goal of this study is to understand how limiting nitrogen in the presence or absence of an ectomycorrhizal fungi, Laccaria bicolor, affects the health of aspen trees, Populus temuloides.

Phytochrome-mediated responses: Implications for controlled environment research facilities

Science.gov (United States)

Smith, Harry

1994-01-01

Light is undoubtedly the most important environmental variable for plant growth and development; plants not only use radiant energy in photosynthesis, they also respond to the quantity, quality, direction and timing of incident radiation through photomorphogenic response that can have huge effects on the rate of growth and the pattern of development. It is surprising, therefore, that the manufacturers and suppliers of controlled environment facilities have been singularly uninventive in the design of the lighting assemblies they provide. The consumer has one choice only - a lighting assembly that provides irradiance levels usually only a fraction of sunlight, and a control system that is limited to regulating the timing of the on-off switch. The reasons for these limitations are partly technological, but in the main they result from ignorance on the part of both the consumer and the manufacturer. A specific and powerful example of this ignorance relates to the importance of the so-called far-red wavelengths (FR = 700-800 nm). Because the human eye can hardly detect wavelengths above 700 nm, and photosynthesis also cuts off at about 700 nm, the majority of plant and crop physiologists are still almost completely unaware that FR radiation can have massive effects on growth rate and development. In consequence, most growth cabinets have light sources based on fluorescent tubes, and provide very little FR apart from that emitted by a token number of small incandescent bulbs. Larger growth facilities often use broader spectrum light sources, but growth facilities that provide the capability to vary the FR incident upon the plants are about as abundant as seals in the Sahara. This article sets the background of the significance of FR radiation in the natural environment and its importance for plant growth and development in the hope that it might inform intelligently those concerned with improving the design of plant growth facilities.

Phytochrome-mediated responses implications for controlled environment research facilities

Energy Technology Data Exchange (ETDEWEB)

Smith, H. [Univ. of Leicester (United Kingdom)

1994-12-31

Light is undoubtedly the most important environmental variable for plant growth and development; plants not only use radiant energy in photosynthesis, they also respond to the quantity, quality, direction and timing of incident radiation through photomorphogenic responses that can have huge effects on the rate of growth and the pattern of development. It is surprising, therefore, that the manufacturers and suppliers of controlled environment facilities have been singularly uninventive in the design of the lighting assemblies they provide. The consumer has one choice only - a lighting assembly that provides irradiance levels usually only a fraction of sunlight, and a control system that is limited to regulating the timing of the on-off switch. The reasons for these limitations are partly technological, but in the main they result from ignorance on the part of both the consumer and the manufacturer. A specific and powerful example of this ignorance relates to the importance of the so-called far-red wavelengths (FR = 700-800 nm). Because the human eye can hardly detect wavelengths above 700 nm, and photosynthesis also cuts off at ca. 700 mn, the majority of plant and crop physiologists are still almost completely unaware that FR radiation can have massive effects on growth rate and development. In consequence, most growth cabinets have light sources based on fluorescent tubes, and provide very little FR apart from that emitted by a token number of small incandescent bulbs. Larger growth facilities often use broader spectrum light sources, but growth facilities that provide the capability to vary the FR incident upon the plants are about as abundant as seals in the Sahara. This article sets the background of the significance of FR radiation in the natural environment and its importance for plant growth and development in the hope that it might inform intelligently those concerned with improving the design of plant growth facilities.

Effects of changes in nutrient loading and composition on hypoxia dynamics and internal nutrient cycling of a stratified coastal lagoon

Science.gov (United States)

Zhu, Yafei; McCowan, Andrew; Cook, Perran L. M.

2017-10-01

The effects of changes in catchment nutrient loading and composition on the phytoplankton dynamics, development of hypoxia and internal nutrient dynamics in a stratified coastal lagoon system (the Gippsland Lakes) were investigated using a 3-D coupled hydrodynamic biogeochemical water quality model. The study showed that primary production was equally sensitive to changed dissolved inorganic and particulate organic nitrogen loads, highlighting the need for a better understanding of particulate organic matter bioavailability. Stratification and sediment carbon enrichment were the main drivers for the hypoxia and subsequent sediment phosphorus release in Lake King. High primary production stimulated by large nitrogen loading brought on by a winter flood contributed almost all the sediment carbon deposition (as opposed to catchment loads), which was ultimately responsible for summer bottom-water hypoxia. Interestingly, internal recycling of phosphorus was more sensitive to changed nitrogen loads than total phosphorus loads, highlighting the potential importance of nitrogen loads exerting a control over systems that become phosphorus limited (such as during summer nitrogen-fixing blooms of cyanobacteria). Therefore, the current study highlighted the need to reduce both total nitrogen and total phosphorus for water quality improvement in estuarine systems.

Effects of changes in nutrient loading and composition on hypoxia dynamics and internal nutrient cycling of a stratified coastal lagoon

Directory of Open Access Journals (Sweden)

Y. Zhu

2017-10-01

Full Text Available The effects of changes in catchment nutrient loading and composition on the phytoplankton dynamics, development of hypoxia and internal nutrient dynamics in a stratified coastal lagoon system (the Gippsland Lakes were investigated using a 3-D coupled hydrodynamic biogeochemical water quality model. The study showed that primary production was equally sensitive to changed dissolved inorganic and particulate organic nitrogen loads, highlighting the need for a better understanding of particulate organic matter bioavailability. Stratification and sediment carbon enrichment were the main drivers for the hypoxia and subsequent sediment phosphorus release in Lake King. High primary production stimulated by large nitrogen loading brought on by a winter flood contributed almost all the sediment carbon deposition (as opposed to catchment loads, which was ultimately responsible for summer bottom-water hypoxia. Interestingly, internal recycling of phosphorus was more sensitive to changed nitrogen loads than total phosphorus loads, highlighting the potential importance of nitrogen loads exerting a control over systems that become phosphorus limited (such as during summer nitrogen-fixing blooms of cyanobacteria. Therefore, the current study highlighted the need to reduce both total nitrogen and total phosphorus for water quality improvement in estuarine systems.

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

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

Vegetated treatment area (VTAs efficiencies for E. coli and nutrient removal on small-scale swine operations

Directory of Open Access Journals (Sweden)

R. Daren Harmel

2018-06-01

Full Text Available As small-scale animal feeding operations work to manage their byproducts and avoid regulation, they need practical, cost-effective methods to reduce environmental impact. One such option is using vegetative treatment areas (VTAs with perennial grasses to treat runoff; however, research is limited on VTA effectiveness as a waste management alternative for smaller operations. This study evaluated the efficiencies of VTAs in reducing bacteria and nutrient runoff from small-scale swine operations in three counties in Central Texas. Based on 4 yr of runoff data, the Bell and Brazos VTAs significantly reduced loads and concentrations of E. coli and nutrients (except NO3-N and had treatment efficiencies of 73–94%. Most notably, the Bell VTA reduced loads of E. coli, NH4-N, PO4-P, total N, and total P similar to that of the background (control. In spite of significant reductions, runoff from the Brazos VTA had higher concentrations and loads than the control site, especially following installation of concrete pens and increased pen washing, which produced standing water and increased E. coli and nutrient influx. The Robertson VTA produced fewer significant reductions and had lower treatment efficiencies (29–69%; however, E. coli and nutrient concentrations and loads leaving this VTA were much lower than observed at the Bell and Brazos County sites due to alternative solids management and enclosed pens. Based on these results and previous research, VTAs can be practical, effective waste management alternatives for reducing nutrient and bacteria losses from small-scale animal operations, but only if properly designed and managed. Keywords: Bacteria, Nutrients, Swine manure, Waste management, Water quality

Ultra-processed foods and the limits of product reformulation.

Science.gov (United States)

Scrinis, Gyorgy; Monteiro, Carlos Augusto

2018-01-01

The nutritional reformulation of processed food and beverage products has been promoted as an important means of addressing the nutritional imbalances in contemporary dietary patterns. The focus of most reformulation policies is the reduction in quantities of nutrients-to-limit - Na, free sugars, SFA, trans-fatty acids and total energy. The present commentary examines the limitations of what we refer to as 'nutrients-to-limit reformulation' policies and practices, particularly when applied to ultra-processed foods and drink products. Beyond these nutrients-to-limit, there are a range of other potentially harmful processed and industrially produced ingredients used in the production of ultra-processed products that are not usually removed during reformulation. The sources of nutrients-to-limit in these products may be replaced with other highly processed ingredients and additives, rather than with whole or minimally processed foods. Reformulation policies may also legitimise current levels of consumption of ultra-processed products in high-income countries and increased levels of consumption in emerging markets in the global South.

Competition for nutrients and light: testing advances in resource competition with a natural phytoplankton community

NARCIS (Netherlands)

Burson, A.; Stomp, M.; Greenwell, E.; Grosse, J.; Huisman, J.

2018-01-01

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,

Treatment of Synthetic Wastewater by Aerobic¬-anaerobic Bioreactor with Granular Sludge Developed for Removal of Nutrients

Directory of Open Access Journals (Sweden)

Malihe Amini

2014-05-01

Full Text Available The excessive accumulation of nutrient (C, N, and P discharge to surface water can pose serious ecological problems that affect the health of aquatic life and consequently that of human and animals. It is, therefore, necessary to remove these substances from wastewaters for reducing their harm to environments. A novel upflow aerobic/anoxic flocculated sludge bioreactor (UAASB will be establish and apply as a single treatment unit for carbon, nitrogen and phosphorus removal. In this study, nutrients (C, N and P removal efficiency in a time-based control UAASB reactor has studied. Analyze of nutrients removal efficiency were investigated from wastewater using optimization of factors and effects of variables: COD/N/P ratio and flow rate. Results of experiments showed that COD/N/P ratio 1000/250/2 and Q 7 L/h in HRT 6 h, F/M 0.054 kg COD/kg MLVSS.h and OLR 0.15 kg/m3.h were desirable for removal of nutrients from wastewater in aerobic/anaerobic bioreactor. In these conditions SVI 53.12 mL/g, COD removal efficiency 86% and PO43- removal efficiency 97.5% were showed. According all results of responses for best nutrient removal, UAASB bioreactor is desirable for removal efficiency of C and P.

Nutrient Management in Pine Forests

Science.gov (United States)

Allan E. Tiarks

1999-01-01

Coastal plain soils are naturally low in fertility and many pine stands will give an economic response to fertilization, especially phosphorus. Maintaining the nutrients that are on the site by limiting displacement of logging slash during and after the harvest can be important in maintaining the productivity of the site and reducing the amount of fertilizer required...

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 ...

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

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.

Expert System Control of Plant Growth in an Enclosed Space

Science.gov (United States)

May, George; Lanoue, Mark; Bathel, Matthew; Ryan, Robert E.

2008-01-01

The Expert System is an enclosed, controlled environment for growing plants, which incorporates a computerized, knowledge-based software program that is designed to capture the knowledge, experience, and problem-solving skills of one or more human experts in a particular discipline. The Expert System is trained to analyze crop/plant status, to monitor the condition of the plants and the environment, and to adjust operational parameters to optimize the plant-growth process. This system is intended to provide a way to remotely control plant growth with little or no human intervention. More specifically, the term control implies an autonomous method for detecting plant states such as health (biomass) or stress and then for recommending and implementing cultivation and/or remediation to optimize plant growth and to minimize consumption of energy and nutrients. Because of difficulties associated with delivering energy and nutrients remotely, a key feature of this Expert System is its ability to minimize this effort and to achieve optimum growth while taking into account the diverse range of environmental considerations that exist in an enclosed environment. The plant-growth environment for the Expert System could be made from a variety of structures, including a greenhouse, an underground cavern, or another enclosed chamber. Imaging equipment positioned within or around the chamber provides spatially distributed crop/plant-growth information. Sensors mounted in the chamber provide data and information pertaining to environmental conditions that could affect plant development. Lamps in the growth environment structure supply illumination, and other additional equipment in the chamber supplies essential nutrients and chemicals.

Neuronal regulation of homeostasis by nutrient sensing.

Science.gov (United States)

Lam, Tony K T

2010-04-01

In type 2 diabetes and obesity, the homeostatic control of glucose and energy balance is impaired, leading to hyperglycemia and hyperphagia. Recent studies indicate that nutrient-sensing mechanisms in the body activate negative-feedback systems to regulate energy and glucose homeostasis through a neuronal network. Direct metabolic signaling within the intestine activates gut-brain and gut-brain-liver axes to regulate energy and glucose homeostasis, respectively. In parallel, direct metabolism of nutrients within the hypothalamus regulates food intake and blood glucose levels. These findings highlight the importance of the central nervous system in mediating the ability of nutrient sensing to maintain homeostasis. Futhermore, they provide a physiological and neuronal framework by which enhancing or restoring nutrient sensing in the intestine and the brain could normalize energy and glucose homeostasis in diabetes and obesity.

Robot motion control in mobile environment

Institute of Scientific and Technical Information of China (English)

Iliya V Miroshnik; HUANG Xian-lin(黄显林); HE Jie(贺杰)

2003-01-01

With the problem of robot motion control in dynamic environment represented by mobile obstacles,working pieces and external mechanisms considered, a relevant control actions design procedure has been pro-posed to provide coordination of robot motions with respect to the moving external objects so that an extension ofrobot spatial motion techniques and active robotic strategies based on approaches of nonlinear control theory canbe achieved.

Activation of CO2-reducing methanogens in oil reservoir after addition of nutrient.

Science.gov (United States)

Yang, Guang-Chao; Zhou, Lei; Mbadinga, Serge Maurice; You, Jing; Yang, Hua-Zhen; Liu, Jin-Feng; Yang, Shi-Zhong; Gu, Ji-Dong; Mu, Bo-Zhong

2016-12-01

Nutrient addition as part of microbial enhanced oil recovery (MEOR) operations have important implications for more energy recovery from oil reservoirs, but very little is known about the in situ response of microorganisms after intervention. An analysis of two genes as biomarkers, mcrA encoding the key enzyme in methanogenesis and fthfs encoding the key enzyme in acetogenesis, was conducted during nutrient addition in oil reservoir. Clone library data showed that dominant mcrA sequences changed from acetoclastic (Methanosaetaceae) to CO 2 -reducing methanogens (Methanomicrobiales and Methanobacteriales), and the authentic acetogens affiliated to Firmicutes decreased after the intervention. Principal coordinates analysis (PCoA) and Jackknife environment clusters revealed evidence on the shift of the microbial community structure among the samples. Quantitative analysis of methanogens via qPCR showed that Methanobacteriales and Methanomicrobiales increased after nutrient addition, while acetoclastic methanogens (Methanosaetaceae) changed slightly. Nutrient treatment activated native CO 2 -reducing methanogens in oil reservoir. The high frequency of Methanobacteriales and Methanomicrobiales (CO 2 -reducers) after nutrient addition in this petroleum system suggested that CO 2 -reducing methanogenesis was involved in methane production. The nutrient addition could promote the methane production. The results will likely improve strategies of utilizing microorganisms in subsurface environments. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Nutrient Management Approaches and Tools for Dairy farms in Australia and the USA.

Science.gov (United States)

In Australia and the USA, nutrient imports and accumulation on dairy farms can be a problem and may pose a threat to the greater environment. While the major nutrient imports onto dairy farms (i.e. fertilizer and feed) and exports (i.e. milk and animals) are generally the same for confinement-based ...

Understanding the Geographic Controls of Hazardous Convective Weather Environments in the United States

Science.gov (United States)

Reed, K. A.; Chavas, D. R.

2017-12-01

Hazardous Convective Weather (HCW), such as severe thunderstorms and tornadoes, poses significant risk to life and property in the United States every year. While these HCW events are small scale, they develop principally within favorable larger-scale environments (i.e., HCW environments). Why these large-scale environments are confined to specific regions, particularly the Eastern United States, is not well understood. This can, in part, be related to a limited fundamental knowledge of how the climate system creates HCW environment, which provides uncertainty in how HCW environments may be altered in a changing climate. Previous research has identified the Gulf of Mexico to the south and elevated terrain upstream as key geographic contributors to the generation of HCW environments over the Eastern United States. This work investigates the relative role of these geographic features through "component denial" experiments in the Community Atmosphere Model version 5 (CAM5). In particular, CAM5 simulations where topography is removed (globally and regionally) and/or the Gulf of Mexico is converted to land is compared to a CAM5 control simulation of current climate following the Atmospheric Model Intercomparison Project (AMIP) protocols. In addition to exploring differences in general characteristics of the large-scale environments amongst the experiments, HCW changes will be explored through a combination of high shear and high Convective Available Potential Energy (CAPE) environments. Preliminary work suggests that the removal of elevated terrain reduces the inland extent of HCW environments in the United States, but not the existence of these events altogether. This indicates that topography is crucial for inland HCW environments but perhaps not for their existence in general (e.g., near the Gulf of Mexico). This initial work is a crucial first step to building a reduced-complexity framework within CAM5 to quantify how land-ocean contrast and elevated terrain control

Control of wheeled mobile robot in restricted environment

Science.gov (United States)

Ali, Mohammed A. H.; En, Chang Yong

2018-03-01

This paper presents a simulation and practical control system for wheeled mobile robot in restricted environment. A wheeled mobile robot with 3 wheels is fabricated and controlled by proportional derivative active force control (PD-AFC) to move in a pre-planned restricted environment to maintain the tracking errors at zero level. A control system with two loops, outer by PD controller and inner loop by Active Force Control, are designed to control the wheeled mobile robot. Fuzzy logic controller is implemented in the Active force Control to estimate the inertia matrix that will be used to calculate the actual torque applied on the wheeled mobile robot. The mobile robot is tested in two different trajectories, namely are circular and straight path. The actual path and desired path are compared.

Effects of nutrient content claims, sports celebrity endorsements and premium offers on pre-adolescent children's food preferences: experimental research.

Science.gov (United States)

Dixon, H; Scully, M; Niven, P; Kelly, B; Chapman, K; Donovan, R; Martin, J; Baur, L A; Crawford, D; Wakefield, M

2014-04-01

To assess pre-adolescent children's responses to common child-oriented front-of-pack food promotions. Between-subjects, web-based experiment with four front-of-pack promotion conditions on energy-dense and nutrient-poor (EDNP) foods: no promotion [control]; nutrient content claims; sports celebrity endorsements (male athletes) and premium offers. Participants were 1302 grade 5 and 6 children (mean age 11 years) from Melbourne, Australia. Participants chose their preferred product from a randomly assigned EDNP food pack and comparable healthier food pack then completed detailed product ratings. Child-oriented pack designs with colourful, cartooned graphics, fonts and promotions were used. Compared to the control condition, children were more likely to choose EDNP products featuring nutrient content claims (both genders) and sports celebrity endorsements (boys only). Perceptions of nutritional content were enhanced by nutrient content claims. Effects of promotions on some product ratings (but not choice) were negated when children referred to the nutrition information panel. Premium offers did not enhance children's product ratings or choice. Nutrient content claims and sports celebrity endorsements influence pre-adolescent children's preferences towards EDNP food products displaying them. Policy interventions to reduce the impact of unhealthy food marketing to children should limit the use of these promotions. © 2013 The Authors. Pediatric Obesity © 2013 International Association for the Study of Obesity.

Development of an epiphyte indicator of nutrient enrichment. A ...

Science.gov (United States)

An extensive review of the literature on epiphytes on submerged aquatic vegetation (SAV), primarily seagrasses but including some brackish and freshwater rooted macrophytes, was conducted in order to evaluate the evidence for response of epiphyte metrics to increased nutrients. Evidence from field observational studies together with laboratory and field mesocosm experiments was assembled from the literature and evaluated for evidence of a hypothesized positive response to nutrient addition. There was general consistency in the results to confirm that elevated nutrients tended to increase the load of epiphytes on the surface of SAV, in the absence of other limiting factors. In spite of multiple sources of uncontrolled variation, positive relationships of epiphyte load to nutrient concentration or load (either N or P) were often observed along strong anthropogenic or natural nutrient gradients in coastal regions, although response patterns may only be evident for parts of the year. Mesocosm nutrient studies tended to be more common for temperate regions and field addition studies more common for tropical and subtropical regions. Addition of nutrients via the water column tended to elicit stronger epiphyte responses than sediment additions, and may be a factor in the lack of epiphyte response reported in some studies. Mesograzer activity is a critical covariate for epiphyte response under experimental nutrient elevation, but the epiphyte response is highly de

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.

Nutrient fate in aquacultural systems for waste treatment

Energy Technology Data Exchange (ETDEWEB)

Dontje, J.H.; Clanton, C.J.

1999-08-01

Twelve small, recirculating aquacultural systems were operated for livestock waste treatment to determine nutrient fate. Each system consisted of a 730-L fish tank coupled in a recirculating loop with three sand beds (serving as biofilters) in parallel. Fish (Tilapia species) were grown in the tanks while cattails, reed canary grass, and tomatoes were grown in separate sand beds. Swine waste was added to the fish tanks every other day at average rates of 50, 72, 95, and 118 kg-COD/ha/day of fish tank surface (three replications of each loading rate). Water from the fish tanks was filtered through the sand beds three times per day with 20% of the tank volume passing through the sand each day. The systems were operated in a greenhouse for eight months (21 July to 8 March). Aboveground plant matter was harvested at eight-week intervals. The fish were removed after four months and the tanks were restocked with fingerlings. Initial and final nitrogen (N), phosphorus (P), and potassium (K) contents of the system components, as well as that of the harvested plants and fish, were determined. Nutrient balance calculations revealed that 30 to 68% of added N was lost from the systems, probably via denitrification. Nutrient removal by plants was 6 to 18% for N, 8 to 21% for P, and 25 to 71% for K, with tomatoes (foliage and fruit) accounting for the majority of the removal. Plant growth was limited by growing conditions (particularly day length), not be nutrient availability. Fish growth was limited by temperature; thus nutrient extraction by the fish was minimal. Under the conditions of this experiment, the system required supplemental aeration.

Determination of the range of control limits in radioimmunoassay measurements

International Nuclear Information System (INIS)

Fiori, A.M.C.

1981-01-01

A grouping technique is proposed for control limits in radioimmunoassay measurements. It has the advantage of working with control limits of 99.7% without the inconvenience of the confidence intervals. The method is practical and simple. It provides considerable flexibility for the processing of data. As the number of samples increases, the control limits become better defined. (author) [es

CONTROLS OF SEAGRASS EPIPHYTE ABUNDANCE: DOES LIGHT TRUMP NUTRIENTS?

Science.gov (United States)

Epiphytes on seagrass growing in the lower intertidal were examined along an estuarine gradient within Yaquina Bay, Oregon over a period of 4 years. The Yaquina Estuary receives high levels of nutrients from the watershed during the wet season and from the ocean during the dry s...

Internal control in an EDI environment.

OpenAIRE

Bae, Dal Hyeoung

1991-01-01

Approved for public release; distribution in unlimited. Electronic Data Interchange(EDI) is the electronic transmission of standard business documents in machine-readable format between parent companies and respective trading partners. As the use of EDI has grown, there have been the associated risks due to an uncontrolled environment. Accordingly, the necessity for effective internal controls in an EDI environment is on the rise. This thesis evaluates and analyzes the feasi...

A development environment for the SSC control system

International Nuclear Information System (INIS)

Murray, Doug; Martinsen, Garth; Wang, Judy

1994-01-01

The SSC is developing a design environment for control system development within the context of EPICS. The environment is aimed at developers of applications using the EPICS Input/Output Controller (IOC). The unique aspect of this effort is our emphasis on providing a simple and intuitive development environment compared with tools currently available. Our most important goal in this effort has been to hide the complexity of EPICS IOC development from the developers. This paper describes two tools which are under development; The Function Block Editor (FBE) and the State Machine Editor (SME). The FBE provides a visual editing environment for graphically describing control processes as a set of related functional blocks. The configuration of functional blocks is then translated into IOC records and executed. SME allows the user to visually construct a sequence using a notation we are modeling after Grafcet [1]. State machines are translated into EPICS State Notation Language programs and executed. Future extensions will be described. ((orig.))

Fresh meteoric versus recirculated saline groundwater nutrient inputs into a subtropical estuary

International Nuclear Information System (INIS)

Sadat-Noori, Mahmood; Santos, Isaac R.; Tait, Douglas R.; Maher, Damien T.

2016-01-01

The role of groundwater in transporting nutrients to coastal aquatic systems has recently received considerable attention. However, the relative importance of fresh versus saline groundwater-derived nutrient inputs to estuaries and how these groundwater pathways may alter surface water N:P ratios remains poorly constrained. We performed detailed time series measurements of nutrients in a tidal estuary (Hat Head, NSW, Australia) and used radium to quantify the contribution of fresh and saline groundwater to total surface water estuarine exports under contrasting hydrological conditions (wet and dry season). Tidally integrated nutrient fluxes showed that the estuary was a source of nutrients to the coastal waters. Dissolved inorganic nitrogen (DIN) export was 7-fold higher than the average global areal flux rate for rivers likely due to the small catchment size, surrounding wetlands and high groundwater inputs. Fresh groundwater discharge was dominant in the wet season accounting for up to 45% of total dissolved nitrogen (TDN) and 48% of total dissolved phosphorus (TDP) estuarine exports. In the dry season, fresh and saline groundwater accounted for 21 and 33% of TDN export, respectively. The combined fresh and saline groundwater fluxes of NO_3, PO_4, NH_4, DON, DOP, TDN and TDP were estimated to account for 66, 58, 55, 31, 21, 53 and 47% of surface water exports, respectively. Groundwater-derived nitrogen inputs to the estuary were responsible for a change in the surface water N:P ratio from typical N-limiting conditions to P-limiting as predicted by previous studies. This shows the importance of both fresh and saline groundwater as a source of nutrients for coastal productivity and nutrient budgets of coastal waters. - Highlights: • Groundwater TDN and TDP fluxes account for 53 and 47% of surface water exports. • The estuary DIN export was 7-fold higher than the average global areal flux. • Fresh GW nutrient input dominated the wet season and saline GW the

Heterologous expression of Anabaena PCC 7120 all3940 (a Dps family gene) protects Escherichia coli from nutrient limitation and abiotic stresses

International Nuclear Information System (INIS)

Narayan, Om Prakash; Kumari, Nidhi; Rai, Lal Chand

2010-01-01

This study presents first hand data on the cloning and heterologous expression of Anabaena PCC 7120 all3940 (a dps family gene) in combating nutrients limitation and multiple abiotic stresses. The Escherichia coli transformed with pGEX-5X-2-all3940 construct when subjected to iron, carbon, nitrogen, phosphorus limitation and carbofuron, copper, UV-B, heat, salt and cadmium stress registered significant increase in growth over the cells transformed with empty vector under iron (0%), carbon (0.05%), nitrogen (3.7 mM) and phosphorus (2 mM) limitation and carbofuron (0.025 mg ml -1 ), CuCl 2 (1 mM), UV-B (10 min), heat (47 o C), NaCl (6% w/v) and CdCl 2 (4 mM) stress. Enhanced expression of all3940 gene measured by semi-quantitative RT-PCR at different time points under above mentioned treatments clearly demonstrates its role in tolerance against aforesaid abiotic stresses. This study opens the gate for developing transgenic cyanobacteria capable of growing successfully under above mentioned stresses.

Monitored natural attenuation study of flood-borne nutrient run-offs in the marine environment of Napti, Batan, Aklan

International Nuclear Information System (INIS)

Sucgang, Raymond J.; Jamangal, Gorgonio; Manuntag, Monica; Templonuevo, Javie Gabriel; Wong, Carlene Dianne; Campos, Ace Bryan; Rafailes, Ma. Cherry

2015-01-01

Climate change-effected flooding transmits land-based nutrients to the marine environment. In this study, nitrate and phosphate levels in sediment and water were measured and compared in six sites in Napti, Batan, Aklan : Site 1-nerritic zone receiving flood water from waterways connected to agricultural areas; Site 2- intertidal community with mangal mangrove vegetation upstream of site 1; Site 3- waterway upstream of site 2; Site 4 - another area of waterway upstream of sites 1&2; SIte 5 - nipa mangrove plantation area upstream of site 4, and Site 6 - waterway upstream of sites 1 to 5 and in close proximity to agricultural areas. Soil and water chemistry were determined during pre and post typhoon Yolanda (Haiyan) flood event, using ion chromatography; bicarbonate was determined by titrimetry. Post flood measurements were performed in two sampling regimes, four months aprat. An average loading rate of nitrated at ∼15 parts per million/day was observed in all the sites. Concentrations of ions were significantly diminished (more than 10 times), during the second post flood measurement in sites with riparian vegetation (sites 2&5) while no significant changes in pollutant concentrations were found in the other sites without riparian vegetation. Conditions that maximize nitrate and nutrient removal in sediments were found to be neutral pH, high bicarbonate, and anoxic conditions. Evidences of denitrification and natural attenuation of pollutants by riparian vegetation were established in the study. (author)

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

Dual Axis Controller for Extreme Environments, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The Dual Axis Controller for Extreme Environments (DACEE) addresses a critical need of NASA's future exploration plans to investigate extreme environments within our...

Recycle of Inorganic Nutrients for Hydroponic Crop Production Following Incineration of Inedible Biomass

Science.gov (United States)

Bubenheim, David L.; Wignarajah, Kanapathipillai; Kliss, Mark H. (Technical Monitor)

1996-01-01

Recovery of resources from waste streams is essential for future implementation and reliance on a regenerative life support system. The major waste streams of concern are from human activities and plant wastes. Carbon, water and inorganics are the primary desired raw materials of interest. The goal of resource recovery is maintenance of product quality to insure support of reliable and predictable levels of life support function performance by the crop plant component. Further, these systems must be maintained over extended periods of time, requiring maintenance of nutrient solutions to avoid toxicity and deficiencies. Today, reagent grade nutrients are used to make nutrient solutions for hydroponic culture and these solutions are frequently changed during the life cycle or sometimes managed for only one crop life cycle. The focus of this study was to determine the suitability of the ash product following incineration of inedible biomass as a source of inorganic nutrients for hydroponic crop production. Inedible wheat biomass was incinerated and ash quality characterized. The incinerator ash was dissolved in adequate nitric acid to establish a consistent nitrogen concentration in all nutrient solution treatments. Four experimental nutrient treatments were included: control, ash only, ash supplemented to match control, and ash only quality formulated with reagent grade chemicals. When nutrient solutions are formulated using only ash following-incineration of inedible biomass, a balance in solution is established representing elemental retention following incineration and nutrient proportions present in the original biomass. The resulting solution is not identical to the control. This imbalance resulted in suppression of crop growth. When the ash is supplemented with nutrients to establish the same balance as in the control, growth is identical to the control. The ash appears to carry no phytotoxic materials. Growth in solution formulated with reagent grade chemicals