Species and biogeochemical cycles of organic phosphorus in sediments from a river with different aquatic plants located in Huaihe River Watershed, China.

Science.gov (United States)

Yuan, He Zhong; Pan, Wei; Ren, Li Jun; Liu, Eeng Feng; Shen, Ji; Geng, Qi Fang; An, Shu Qing

2015-01-01

The results of phosphorus fractionation in the sediments from a contaminated river containing different aquatic plants, analyzed by solution 31P-NMR for Organic Phosphorus, showed that the concentration of Inorganic Phosphorus dominated in all species and Organic Phosphorus accounted for over 20% of Total Phosphorus. In general, orthophosphate was dominant in all the sampling sites. The proportion of Organic Phosphorus accounting for the Total Phosphorus in the sediments with different plant decreased in the following order: Paspalum distichum>Typha orientalis>Hydrilla verticillata. Phosphorus-accumulation ability of Paspalum distichum was obviously stronger than Typha orientalis and Hydrilla verticillata. The Organic Phosphorus was in aquatic plants dominated by humic-associated P (Hu-P), which converted to Inorganic Ohosphorus more significantly in submerged plants than in emerged plants. The sediment dominated by Paspalum distichum abundantly accumulated Organic Phosphorus in the orthophosphate monoester fraction. The degradation and mineralization of orthophosphate monoester was the important source of high Inorganic Phosphorus concentration and net primary productivity in Suoxu River. The Organic Phosphorus derived from Typha orientalis and Hydrilla verticillata was dramatically converted to Inorganic Phosphorus when the environmental factors varied.

Effects of the decomposing liquid of Cladophora oligoclona on Hydrilla verticillata turion germination and seedling growth.

Science.gov (United States)

Zhang, Lu; Peng, Xue; Liu, Biyun; Zhang, Yi; Zhou, Qiaohong; Wu, Zhenbin

2018-08-15

Excessive proliferation of filamentous green algae (FGA) has been considered an important factor resulting in the poor growth or even decline of submerged macrophytes. However, there is a lack of detailed information regarding the effect of decaying FGA on submerged macrophytes. This study aimed to investigate whether the decomposing liquid from Cladophora oligoclona negatively affects Hydrilla verticillata turion germination and seedling growth. The results showed that the highest concentrations of decomposing liquid treatments inhibited the turion germination rate, which was the lowest than other treatments, at only 84%. The chlorophyll a fluorescence (JIP test) and physiological indicators (chlorophyll a content, soluble sugars, Ca 2+ /Mg 2+ -ATPase and PAL activity) were also measured. The chlorophyll a content in the highest concentration (40% of original decomposing liquid) treatment group decreased by 43.53% than that of the control; however, soluble sugars, Ca 2+ /Mg 2+ -ATPase, and PAL activity increased by 172.46%, 271.19%, and 26.43% respectively. The overall results indicated that FGA decay has a considerable effect on submerged macrophyte turion germination and seedling growth, which could inhibit their expansion and reproduction. This study emphasized the need to focus on effects of FGA decomposition on the early growth stages of submerged macrophytes and offered technological guidance for submerged vegetation restoration in lakes and shallow waters. Copyright © 2018 Elsevier Inc. All rights reserved.

Acclimation of a terrestrial plant to submergence facilitates gas exchange under water

DEFF Research Database (Denmark)

Mommer, L.; Pedersen, O.; Visser, E. J. W.

2004-01-01

Flooding imposes stress upon terrestrial plants since it severely hampers gas exchange rates between the shoot and the environment. The resulting oxygen deficiency is considered to be the major problem for submerged plants. Oxygen microelectrode studies have, however, shown that aquatic plants...... of this terrestrial plant species to submergence for gas exchange capacity is also shown. Shoot acclimation to submergence involved a reduction of the diffusion resistance to gases, which was not only functional by increasing diffusion of oxygen into the plant, but also by increasing influx of CO2, which enhances...... maintain relatively high internal oxygen pressures under water, and even may release oxygen via the roots into the sediment, also in dark. Based on these results, we challenge the dogma that oxygen pressures in submerged terrestrial plants immediately drop to levels at which aerobic respiration is impaired...

Evaluation of butachlor for control of some submerged macrophytes along with its impact on biotic components of freshwater system

Directory of Open Access Journals (Sweden)

A. Chattopadhyay, S. Adhikari, S. P. Adhikary, S. Ayyappan

2006-04-01

Full Text Available In this investigation, the efficacy of the herbicide butachlor, (N-butoxymethyl-2 chloro-21, 61 diethyl acetanilide was tested against few common submerged macrophytes namely Hydrilla (Hydrilla verticillata (L. Royale, Najas (Najas minor All., Nechamandra (Nechamandra alternifolia (Roxb. Thwaites and Ottelia (Ottelia alismoides (L. Pers. of freshwater fish ponds. Almost complete decay of Hydrilla, Nechamandra and Ottelia was achieved at 7.5 L of active ingredient/ha/m butachlor within 15 days while the herbicide showed no negative effect on Najas. However at the same concentration of butachlor, total mortality of zooplankton and water fern Azolla (Azolla caroliniana Lamarck occurred within seven days. In case of few freshwater fish species like Rohu (Labeo rohita, Channa (Channa punctatus, Anabas (Anabas testitudineus and Heteropneustes (Heteropneustes fossilis, total mortality occurred upto 90 days after application of the same dose of butachlor but fish survived beyond 120 days of herbicide application indicating degradation of the herbicides.

Assessment of Nelumbo nucifera and Hydrilla verticillata in the treatment of pharmaceutical industry effluent from 24 Parganas, West Bengal

Directory of Open Access Journals (Sweden)

Shamba Chatterjee

2014-10-01

Full Text Available Modern day technologies employed in industrialization and unhygienic lifestyle of mankind has led to a severe environmental menace resulting in pollution of freshwater bodies. Pharmaceutical industry effluents cause eutrophication and provide adequate nutrients for growth of pathogenic bacteria. This study has been conducted with aquatic plants water lotus (Nelumbo nucifera and hydrilla (Hydrilla verticillata with an novel aim to treat pharmaceutical industry effluents showing the outcome of the experiments carried out with the effluents collected from rural areas of 24 Parganas, West Bengal, India. Determination of pH, solid suspend, BOD5, NH3-N, MPN and coliform test were used for this notioned purpose. Pharmaceutical waste effluent water treated with water lotus showed less pH, solid suspend, DO, BOD, NH3-N, MPN and coliform bacteria than hydrilla treatment when compared to the control. In conclusion, water lotus is found to be more efficient in treatment of pharmaceutical industry effluent waste water than hydrilla.

Through-flow of water in leaves of a submerged plant is influenced by the apical opening

DEFF Research Database (Denmark)

Pedersen, Ole; Jørgensen, Lise Bolt; Sand-Jensen, Kaj

1997-01-01

Submerged plant, apical opening, hydathode, Sparganium, hydraulic architecture, leaf specific conductivity......Submerged plant, apical opening, hydathode, Sparganium, hydraulic architecture, leaf specific conductivity...

Exploration for Natural Enemies of Hydrilla verticillata in Eastern Africa.

Science.gov (United States)

1980-05-01

mandibles and heads than the scavengers. Bill Beck of Florida A&M University, who identified the hydrilla midge as a species of Polypedilum, feels...that the head and mandibles of this midge resemble those of the scavenger section instead of the herbivore section of the genus, as the types occur in...Lakshmanan, K. K. 1965. " Embryological Studies in the Hydrocharitaceae. IV. Post-Fertilization Development in Hydrilla verticillata Royle," Phyton Rev

Gas exchange under water. Acclimation of terrestrial plants to submergence

NARCIS (Netherlands)

Mommer, L.

2005-01-01

Gas exchange between the plant and the environment is severely hampered when plants are submerged, leading to oxygen and energy deficits. A straightforward way to reduce these shortages of oxygen and carbohydrates would be prolonged photosynthesis under water, but this has received only little

Acclimation of Hydrilla verticillata to sediment anoxia in vegetation restoration in eutrophic waters.

Science.gov (United States)

Wu, Juan; Dai, Yanran; Rui, Shengyang; Cui, Naxin; Zhong, Fei; Cheng, Shuiping

2015-12-01

Sediment anoxia generally results from intense organic enrichment and is a limiting factor in the restoration of vegetation in eutrophic waters. To investigate the effect of sediment anoxia on a typical pollution-tolerant submerged macrophyte species, Hydrilla verticillata, and acclimation mechanisms in the plant, a gradient of sediment anoxia was simulated with additions of sucrose to the sediment, which can stimulate increased concentrations of total nitrogen, NH4(+) and Fe in pore water. H. verticillata growth was significantly affected by highly anoxic conditions, as indicated by reduced total biomass in the 0.5 and 1% sucrose treatments. However, slight anoxia (0.1% sucrose addition) promoted growth, and the shoot biomass was 22.64% higher than in the control. In addition to morphologic alterations, H. verticillata showed physiological acclimations to anoxia, including increased anaerobic respiration and changes in carbon and nitrogen metabolism in roots. The soluble protein and soluble carbohydrate contents in roots of the 1% treatment were both significantly higher compared with those in the control. The increase in alcohol dehydrogenase activity and pyruvate content in the roots suggested that H. verticillata has a well-developed capacity for anaerobic fermentation. This study suggests that highly anoxic sediments inhibit the growth of H. verticillata and the species has a degree of tolerance to anoxic conditions. Further in situ investigations should be conducted on the interactions between sediment conditions and macrophytes to comprehensively evaluate the roles of sediment in the restoration of vegetation in eutrophic waters.

Effect of clone size on submergence tolerance and post-submergence growth recovery in Carex brevicuspis (Cyperaceae

Directory of Open Access Journals (Sweden)

Zhengmiao Deng

2016-12-01

Full Text Available Clonal plants are prevalent in wetlands and play important roles in maintaining the functions of the ecosystem. In the present study, we determined the effect of clone sizes (R1, R2, and R3 comprising 1, 3, and 5clumping ramets on the tolerance of Carex brevicuspis growing under 30-cm-deep water to three different periods (one, two, and three months of submergence and its growth recovery one month after de-submergence. Our results showed that the relative growth rate (RGR of C. brevicuspis significantly declined with increasing submergence time, and was higher in R3 and R5 than in R1 plants under both submergence and post-submergence conditions. The concentration of water-soluble carbohydrates (WSCs was highest in R3, intermediate in R5, and the lowest in R1 plants during the first two months of submergence, indicating an optimal trade-off between energy investment and vegetative growth (i.e., buds and ramets production in C. brevicuspis. WSCs were significantly reduced with increasing submergence time, while the starch content was significantly reduced only during the third month of submergence, implying that WSCs were a direct energy source for C. brevicuspis during submergence. The number of buds was higher in R5 than in R3 and R1 plants after two and three months of submergence, which directly resulted in a significantly higher post-submergence ramet production in R5 plants. These results indicated that plants with relatively larger clone sizes display better tolerance to submergence stress and post-submergence growth recovery. Therefore, we speculate that the large clone size in C brevicuspis might be an effective adaptive mechanism to survive under submergence stress in floodplain wetlands.

[Influence of submerged macrophytes on phosphorus transference between sediment and overlying water in the growth period].

Science.gov (United States)

Wang, Li-Zhi; Wang, Guo-Xiang; Yu, Zhen-Fei; Zhou, Bei-Bei; Chen, Qiu-Min; Li, Zhen-Guo

2012-02-01

In order to study the process of phosphorus transfer between sediment and overlying water, Hydrilla verticillata and Vallisneria natans were cultured in spring, Potamogeton crispus was cultured in winter. Changes of environmental factors and phosphorus concentrations in water and sediment were investigated. The results indicated that: submerged macrophytes could reduce all phosphorus fractions in the overlying water. Phosphorus concentrations in overlying water maintained in a relative low level in the growth period of submerged macrophytes. The concentrations of total phosphorus (TP) in overlying water of H. verticillata, V. natans and P. crispus were 0.03-0.05, 0.04-0.12, 0.02-0.11 mg x L(-1), respectively. All phosphorus fractions in sediment were reduced. The maximum value between submerged macrophyte and control of H. verticillata, V. natans and P. crispus were 35.34, 60.67 and 25.92 mg x kg(-1), respectively. Dissolved oxygen (DO), redox potential (Eh) and pH in overlying water increased (DO 10.0-14.0 mg x L(-1), Eh 185-240 mV, pH 8.0-11.0) in the submerged macrophytes groups. Submerged macrophytes increased Eh( -140 - -23 mV) and maintained pH(7.2-8.0) in neutral range. The results indicated that submerged macrophytes affected phosphorus transferring between sediment and overlying water through increasing DO, Eh and pH in overlying water, and Eh in sediment.

Acclimation of a terrestrial plant to submergence facilitates gas exchange under water

NARCIS (Netherlands)

Mommer, L.; Pedersen, O.; Visser, E.J.W.

2004-01-01

Flooding imposes stress upon terrestrial plants since it severely hampers gas exchange rates between the shoot and the environment. The resulting oxygen deficiency is considered to be the major problem for submerged plants. Oxygen microelectrode studies have, however, shown that aquatic plants

A functional comparison of acclimation to shade and submergence in two terrestrial plant species

NARCIS (Netherlands)

Mommer, L.; Kroon, de H.; Pierik, R.; bögemann, G.M.; Visser, E.J.W.

2005-01-01

Terrestrial plants experience multiple stresses when they are submerged, caused both by oxygen deficiency due to reduced gas diffusion in water, and by shade due to high turbidity of the floodwater. It has been suggested that responses to submergence are de facto responses to low light intensity. •

Interspecific competition effects on phosphorus accumulation by Hydrilla verticillata and Vallisneria natans.

Science.gov (United States)

Zhang, Xiufeng; Liu, Zhengwen

2011-01-01

The competition between submersed plants has been recognized as an important factor influencing the structure of plant communities in shallow lakes. The ability of different species to take up and store nutrients from the surrounding ambience varies, and hence plant community structure might be expected to affect the cycling of nutrients in lake ecosystems. In this study, the uptake of phosphorus by Hydrilla verticillata and Vallisneria natans was studied and compared in monoculture and competitive mixed-culture plantings. Results showed that for both studied species the phosphorus concentrations of different tissues and of whole plants was unaffected by competition. However, the quantity of phosphorus accumulated by whole plants of H. verticillata was significantly higher in mixture culture than in monoculture, while that of V. natans was lower in the mixed culture. The results indicated that H. verticillata has a competitive advantage over V. natans, when the two species are grown in competition, and is able to accumulate a greater quantity of phosphorus.

Applying the seedling-emergence method under waterlogged conditions to detect the seed bank of aquatic plants in submerged sediments

NARCIS (Netherlands)

Boedeltje, G; ter Heerdt, GNJ; Bakker, JP

Seed bank studies focused on submerged aquatic plants are generally performed under submerged conditions, using the seedling-emergence method. However, if a study targets at both submerged species and helophytes, submerged conditions are generally not suitable. We tested the emergence of seedlings

Evaluation of uranium removal by Hydrilla verticillata (L.f.) Royle from low level nuclear waste under laboratory conditions.

Science.gov (United States)

Srivastava, Sudhakar; Bhainsa, K C

2016-02-01

The present study evaluated uranium (U) removal ability and tolerance to low level nuclear waste (LLNW) of an aquatic weed Hydrilla verticillata. Plants were screened for growth in 10%-50% waste treatments up to 3 d. Treatments of 20% and 50% waste imposed increasing toxicity with duration assessed in terms of change in fresh weight and in the levels of photosynthetic pigments and thiobarbituric acid-reactive substances. U concentration, however, did not show a progressive increase and was about 42 μg g(-1) dw from 20% to 50% waste at 3 d. This suggested that a saturation stage was reached with respect to U removal due to increasing toxicity. However, in another experiment with 10% waste and 10% waste+10 ppm U treatments, plants showed an increase in U concentration with the maximum level approaching 426 μg g(-1) dw at 3 d without showing any toxicity as compared to that at 20% and 50% waste treatments. Hence, plants possessed significant potential to take up U and toxicity of LLNW limited their U removal ability. This implies that the use of Hydrilla plants for U removal from LLNW is feasible at low concentrations and would require repeated harvesting at short intervals. Copyright © 2015 Elsevier Ltd. All rights reserved.

Studies of Physcomitrella patens reveal that ethylene-mediated submergence responses arose relatively early in land-plant evolution

KAUST Repository

Yasumura, Yuki

2012-10-18

Colonization of the land by multicellular green plants was a fundamental step in the evolution of life on earth. Land plants evolved from fresh-water aquatic algae, and the transition to a terrestrial environment required the acquisition of developmental plasticity appropriate to the conditions of water availability, ranging from drought to flood. Here we show that extant bryophytes exhibit submergence-induced developmental plasticity, suggesting that submergence responses evolved relatively early in the evolution of land plants. We also show that a major component of the bryophyte submergence response is controlled by the phytohormone ethylene, using a perception mechanism that has subsequently been conserved throughout the evolution of land plants. Thus a plant environmental response mechanism with major ecological and agricultural importance probably had its origins in the very earliest stages of the colonization of the land. © 2012 Blackwell Publishing Ltd.

Surveys for Pathogens of Monoecious Hydrilla

Science.gov (United States)

2014-01-01

California ( Madeira et al. 2004). Monoecious hydrilla was first discovered in Delaware in 1976 and later in the Potomac River (Haller 1982, Steward et al...1984). It has now expanded its distribution through the Atlantic States and northward to Maine ( Madeira et al. 2004). Separate populations have...the water surface and then spreading laterally and forming a mat (Van 1989). Madeira et al. (1997) hypothesized that this growth form was an

A new mechanism of macrophyte mitigation: how submerged plants reduce malathion's acute toxicity to aquatic animals.

Science.gov (United States)

Brogan, William R; Relyea, Rick A

2014-08-01

A growing body of evidence suggests that aquatic plants can mitigate the toxicity of insecticides to sensitive aquatic animals. The current paradigm is that this ability is driven primarily by insecticide sorption to plant tissues, especially for hydrophobic compounds. However, recent work shows that submerged plants can strongly mitigate the toxicity of the relatively hydrophilic insecticide malathion, despite the fact that this compound exhibits a slow sorption rate to plants. To examine this disparity, we tested the hypothesis that the mitigating effect of submerged plants on malathion's toxicity is driven primarily by the increased water pH from plant photosynthesis causing the hydrolysis of malathion, rather than by sorption. To do this, we compared zooplankton (Daphnia magna) survival across five environmentally relevant malathion concentrations (0, 1, 4, 6, or 36 μg L(-1)) in test containers where we chemically manipulated water pH in the absence of plants or added the submerged plant (Elodea canadensis) but manipulated plant photosynthetic activity via shading or no shading. We discovered that malathion was equally lethal to Daphnia at all concentrations tested when photosynthetically inactive (i.e. shaded) plants were present (pH at time of dosing=7.8) or when pH was chemically decreased (pH=7.7). In contrast, when photosynthetically active (i.e. unshaded) plants were present (pH=9.8) or when pH was chemically increased (pH=9.5), the effects of 4 and 6 μg L(-1) of malathion on Daphnia were mitigated strongly and to an equal degree. These results demonstrate that the mitigating effect of submerged plants on malathion's toxicity can be explained entirely by a mechanism of photosynthesizing plants causing an increase in water pH, resulting in rapid malathion hydrolysis. Our findings suggest that current ecotoxicological models and phytoremediation strategies may be overlooking a critical mechanism for mitigating pesticides. Copyright © 2014 Elsevier Ltd

Overseas Surveys (1981-1983) for Insects to Control Hydrilla.

Science.gov (United States)

1985-12-01

various aquatic habitats, but no hydrilla was found. Because of the Hari Raya holidays, most hotels were booked and almost a quarter of the total of 1,400...assistant. Mr. Ho spent most of morn- ing telephoning people in Malaysian Agriculture and Irrigation Departments. Because of holidays (Harl Raya ) that

Establishing Research and Management Priorities for Monoecious Hydrilla

Science.gov (United States)

2014-01-01

this definition. Monoecious hydrilla is considered highly invasive in large reservoirs of the Mid- Atlantic states; however, widespread use of grass...drawdowns or fluctuations in water levels, high spring flows, and early spring turbidity (i.e. disturbance) as the dormant tuber bank is largely... West Virginia, Ohio, and Kentucky) are of particular concern, as these infestations may be a source of new and continuing introductions into

Phytoremediation of arsenic in submerged soil by wetland plants.

Science.gov (United States)

Jomjun, Nateewattana; Siripen, Trichaiyaporn; Maliwan, Saeouy; Jintapat, Nateewattana; Prasak, Thavornyutikarn; Somporn, Choonluchanon; Petch, Pengchai

2011-01-01

Wetland aquatic plants including Canna glauca L., Colocasia esculenta L. Schott, Cyperus papyrus L. and Typha angustifolia L. were used in the phytoremediation of submerged soil polluted by arsenic (As). Cyperus papyrus L. was noticed as the largest biomass producer which has arsenic accumulation capacity of 130-172 mg As/kg plant. In terms of arsenic removal rate, however, Colocasia esculenta L. was recognized as the largest and fastest arsenic remover in this study. Its arsenic removal rate was 68 mg As/m2/day while those rates of Canna glauca L., Cyperus papyrus L. and Typha angustifolia L. were 61 mg As/m2/day, 56 mg As/m2/day, and 56 mg As/m2/day, respectively. Although the 4 aquatic plants were inferior in arsenic accumulation, their high arsenic removal rates were observed. Phytostabilization should be probable for the application of these plants.

Do Amplitudes of Water Level Fluctuations Affect the Growth and Community Structure of Submerged Macrophytes?

Science.gov (United States)

Wang, Mo-Zhu; Liu, Zheng-Yuan; Luo, Fang-Li; Lei, Guang-Chun; Li, Hong-Li

2016-01-01

Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii) and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm) of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm) were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions. PMID:26735689

Do Amplitudes of Water Level Fluctuations Affect the Growth and Community Structure of Submerged Macrophytes?

Science.gov (United States)

Wang, Mo-Zhu; Liu, Zheng-Yuan; Luo, Fang-Li; Lei, Guang-Chun; Li, Hong-Li

2016-01-01

Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii) and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm) of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm) were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions.

Do Amplitudes of Water Level Fluctuations Affect the Growth and Community Structure of Submerged Macrophytes?

Directory of Open Access Journals (Sweden)

Mo-Zhu Wang

Full Text Available Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions.

Submergence tolerance in Hordeum marinum

DEFF Research Database (Denmark)

Pedersen, Ole; Malik, Al I.; Colmer, Timothy D.

2010-01-01

Floodwaters differ markedly in dissolved CO(2), yet the effects of CO(2) on submergence responses of terrestrial plants have rarely been examined. The influence of dissolved CO(2) on underwater photosynthesis and growth was evaluated for three accessions of the wetland plant Hordeum marinum Huds....... All three accessions tolerated complete submergence, but only when in CO(2) enriched floodwater. Plants submerged for 7 days in water at air equilibrium (18 mM CO(2)) suffered loss of biomass, whereas those with 200 mM CO(2) continued to grow. Higher underwater net photosynthesis at 200 mM CO(2......) increased by 2.7- to 3.2-fold sugar concentrations in roots of submerged plants, compared with at air equilibrium CO(2). Leaf gas films enhancing gas exchange with floodwater, lack of a shoot elongation response conserving tissue sugars and high tissue porosity (24-31% in roots) facilitating internal O(2...

Effects of snails, submerged plants and their coexistence on eutrophication in aquatic ecosystems

OpenAIRE

Mo Shuqing; Zhang Xiufeng; Tang Yali; Liu Zhengwen; Kettridge Nicholas

2017-01-01

Eutrophication resulting from nutrient loading to freshwater habitats is a severe problem, leading to degradation of ecosystems, including deterioration of water quality, water clarity and loss of biodiversity. Measures enacted to restore degraded freshwater ecosystems often involve the reintroduction of submerged plants and aquatic animals with beneficial ecological functions. In a mesocosm experiment, three treatments (planting with Vallisneria natans, introduction of the snail Bellamya aer...

Oxygen dynamics in submerged rice (Oryza sativa L.)

DEFF Research Database (Denmark)

Colmer, Timothy D.; Pedersen, Ole

2008-01-01

Complete submergence of plants prevents direct O2 and CO2 exchange with air. Underwater photosynthesis can result in marked diurnal changes in O2 supply to submerged plants. Dynamics in pO2 had not been measured directly for submerged rice (Oryza sativa), but in an earlier study, radial O2 loss...... from roots showed an initial peak following shoot illumination.  O2 dynamics in shoots and roots of submerged rice were monitored during light and dark periods, using O2 microelectrodes. Tissue sugar concentrations were also measured.  On illumination of shoots of submerged rice, pO2 increased rapidly...... of magnitude higher than in darkness, enhancing also pO2 in roots.The initial peak in pO2 following illumination of submerged rice was likely to result from high initial rates of net photosynthesis, fuelled by CO2 accumulated during the dark period. Nevertheless, since sugars decline with time in submerged...

Mineralization of Surfactants by the Microbiota of Submerged Plant Detritus

OpenAIRE

Federle, Thomas W.; Ventullo, Roy M.

1990-01-01

In wetlands and canopied bodies of water, plant detritus is an important source of carbon and energy. Detrital materials possess a large surface area for sorption of dissolved organics and are colonized by a large and diverse microbiota. To examine the biodegradation of surfactants by these microorganisms, submerged oak leaves were obtained from a laundromat wastewater pond, its overflow, and a pristine control pond. Leaves were cut into disks and incubated in sterile water amended with 50 μg...

Effects of snails, submerged plants and their coexistence on eutrophication in aquatic ecosystems

Directory of Open Access Journals (Sweden)

Mo Shuqing

2017-01-01

Full Text Available Eutrophication resulting from nutrient loading to freshwater habitats is a severe problem, leading to degradation of ecosystems, including deterioration of water quality, water clarity and loss of biodiversity. Measures enacted to restore degraded freshwater ecosystems often involve the reintroduction of submerged plants and aquatic animals with beneficial ecological functions. In a mesocosm experiment, three treatments (planting with Vallisneria natans, introduction of the snail Bellamya aeruginosa and a combined treatment with both plants and snails were compared with controls to evaluate their effects on trophic state. The total nitrogen (TN, total phosphorus (TP and chlorophyll a (Chl a concentrations of planktonic and benthic algal samples were determined every two weeks, along with light intensity at the sediment surface. The plant-only treatment significantly reduced the TN levels and planktonic and benthic algal biomass and increased the light intensity at the sediment surface. The snail-only treatment reduced the concentrations of TN and reduced planktonic and benthic algal biomass. The combined treatment decreased the concentrations of TN and TP, reduced planktonic algal biomass and increased the light intensity on the sediment surface. The results indicate that while submerged plants and snails can both improve water quality, the most pronounced effect in aquatic ecosystems is achieved by their presence in combination. A combined reintroduction approach may provide enhanced benefits in restoring the eutrophic ecosystems, following the reduction of external nutrient loading.

Studies of Physcomitrella patens reveal that ethylene-mediated submergence responses arose relatively early in land-plant evolution

KAUST Repository

Yasumura, Yuki; Pierik, Ronald; Fricker, Mark D.; Voesenek, Laurentius A. C. J.; Harberd, Nicholas P.

2012-01-01

in the evolution of land plants. We also show that a major component of the bryophyte submergence response is controlled by the phytohormone ethylene, using a perception mechanism that has subsequently been conserved throughout the evolution of land plants. Thus a

Underwater Photosynthesis of Submerged Plants – Recent Advances and Methods

Science.gov (United States)

Pedersen, Ole; Colmer, Timothy D.; Sand-Jensen, Kaj

2013-01-01

We describe the general background and the recent advances in research on underwater photosynthesis of leaf segments, whole communities, and plant dominated aquatic ecosystems and present contemporary methods tailor made to quantify photosynthesis and carbon fixation under water. The majority of studies of aquatic photosynthesis have been carried out with detached leaves or thalli and this selectiveness influences the perception of the regulation of aquatic photosynthesis. We thus recommend assessing the influence of inorganic carbon and temperature on natural aquatic communities of variable density in addition to studying detached leaves in the scenarios of rising CO2 and temperature. Moreover, a growing number of researchers are interested in tolerance of terrestrial plants during flooding as torrential rains sometimes result in overland floods that inundate terrestrial plants. We propose to undertake studies to elucidate the importance of leaf acclimation of terrestrial plants to facilitate gas exchange and light utilization under water as these acclimations influence underwater photosynthesis as well as internal aeration of plant tissues during submergence. PMID:23734154

Separating the effects of partial submergence and soil oxygen demand on plant physiology.

Science.gov (United States)

van Bodegom, Peter M; Sorrell, Brian K; Oosthoek, Annelies; Bakker, Chris; Aerts, Rien

2008-01-01

In wetlands, a distinct zonation of plant species composition occurs along moisture gradients, due to differential flooding tolerance of the species involved. However, "flooding" comprises two important, distinct stressors (soil oxygen demand [SOD] and partial submergence) that affect plant survival and growth. To investigate how these two flooding stressors affect plant performance, we executed a factorial experiment (water depth x SOD) for six plant species of nutrient-rich and nutrient-poor conditions, occurring along a moisture gradient in Dutch dune slacks. Physiological, growth, and biomass responses to changed oxygen availability were quantified for all species. The responses were consistent with field zonation, but the two stressors affected species differently. Increased SOD increased root oxygen deprivation, as indicated by either raised porosity or increased alcohol dehydrogenase (ADH) activity in roots of flood-intolerant species (Calamagrostis epigejos and Carex arenaria). While SOD affected root functioning, partial submergence tended more to reduce photosynthesis (as shown both by gas exchange and 13C assimilation), leaf dark respiration, 13C partitioning from shoots to roots, and growth of these species. These processes were especially affected if the root oxygen supply was depleted by a combination of flooding and increased SOD. In contrast, the most flood-tolerant species (Juncus subnodulosus and Typha latifolia) were unaffected by any treatment and maintained high internal oxygen concentrations at the shoot : root junction and low root ADH activity in all treatments. For these species, the internal oxygen transport capacity was well in excess of what was needed to maintain aerobic metabolism across all treatments, although there was some evidence for effects of SOD on their nitrogen partitioning (as indicated by 865N values) and photosynthesis. Two species intermediate in flooding tolerance (Carex nigra and Schoenus nigricans) responded more

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

A model for the release, dispersion and environmental impact of a postulated reactor accident from a submerged commercial nuclear power plant

Science.gov (United States)

Bertch, Timothy Creston

1998-12-01

Nuclear power plants are inherently suitable for submerged applications and could provide power to the shore power grid or support future underwater applications. The technology exists today and the construction of a submerged commercial nuclear power plant may become desirable. A submerged reactor is safer to humans because the infinite supply of water for heat removal, particulate retention in the water column, sedimentation to the ocean floor and inherent shielding of the aquatic environment would significantly mitigate the effects of a reactor accident. A better understanding of reactor operation in this new environment is required to quantify the radioecological impact and to determine the suitability of this concept. The impact of release to the environment from a severe reactor accident is a new aspect of the field of marine radioecology. Current efforts have been centered on radioecological impacts of nuclear waste disposal, nuclear weapons testing fallout and shore nuclear plant discharges. This dissertation examines the environmental impact of a severe reactor accident in a submerged commercial nuclear power plant, modeling a postulated site on the Atlantic continental shelf adjacent to the United States. This effort models the effects of geography, decay, particle transport/dispersion, bioaccumulation and elimination with associated dose commitment. The use of a source term equivalent to the release from Chernobyl allows comparison between the impacts of that accident and the postulated submerged commercial reactor plant accident. All input parameters are evaluated using sensitivity analysis. The effect of the release on marine biota is determined. Study of the pathways to humans from gaseous radionuclides, consumption of contaminated marine biota and direct exposure as contaminated water reaches the shoreline is conducted. The model developed by this effort predicts a significant mitigation of the radioecological impact of the reactor accident release

Photoinhibition-like damage to the photosynthetic apparatus in plant leaves induced by submergence treatment in the dark.

Directory of Open Access Journals (Sweden)

Xingli Fan

Full Text Available Submergence is a common type of environmental stress for plants. It hampers survival and decreases crop yield, mainly by inhibiting plant photosynthesis. The inhibition of photosynthesis and photochemical efficiency by submergence is primarily due to leaf senescence and excess excitation energy, caused by signals from hypoxic roots and inhibition of gas exchange, respectively. However, the influence of mere leaf-submergence on the photosynthetic apparatus is currently unknown. Therefore, we studied the photosynthetic apparatus in detached leaves from four plant species under dark-submergence treatment (DST, without influence from roots and light. Results showed that the donor and acceptor sides, the reaction center of photosystem II (PSII and photosystem I (PSI in leaves were significantly damaged after 36 h of DST. This is a photoinhibition-like phenomenon similar to the photoinhibition induced by high light, as further indicated by the degradation of PsaA and D1, the core proteins of PSI and PSII. In contrast to previous research, the chlorophyll content remained unchanged and the H2O2 concentration did not increase in the leaves, implying that the damage to the photosynthetic apparatus was not caused by senescence or over-accumulation of reactive oxygen species (ROS. DST-induced damage to the photosynthetic apparatus was aggravated by increasing treatment temperature. This type of damage also occurred in the anaerobic environment (N2 without water, and could be eliminated or restored by supplying air to the water during or after DST. Our results demonstrate that DST-induced damage was caused by the hypoxic environment. The mechanism by which DST induces the photoinhibition-like damage is discussed below.

Field Surveys to Identify Biocontrol Agents of Hydrilla verticillata from June - September 2012

Science.gov (United States)

2015-07-01

taxonomists for full identification. Chironomid larvae damaging tips and emerging adults were collected from hydrilla at Chetian Town, Lizui Town, and...R. S. Arias, B. E. Scheffler, S. O. Duke, M. Netherland, F. E. Dayan. 2004. Somatic mutation-mediated evolution of herbicide resistance in the

Modified Application of Nitrogen Fertilizer for Increasing Rice Variety Tolerance toward Submergence Stress

Directory of Open Access Journals (Sweden)

Gribaldi Gribaldi

2017-01-01

Full Text Available This research was conducted from July to October 2015, using Randomized Block Design with two treatment factors and three replications for each treatment. The first factor was rice varieties (V: V1 = IR 64; V2 = Inpara 5. The second factor was fertilizer (N: N0: without submergence, all N fertilizer was given during planting; N1: all N fertilizer dose was given during planting; and N2: 1/2 dose of N fertilizer was given during planting; the rest was given at 42 days after planting. The submergence was during 7–14 days after planting; N3 = the entire dose of N fertilizer that was given during planting, N4 = 1/2 the dose of N fertilizer that was given during planting, and the rest was given at 42 days after planting. The submergence was during 7–14 and 28–35 days after planting. The results showed that the management of nitrogen fertilizer application had effect on rice growth and production which experienced dirty water submergence stress; the application of 1/2 dose of N fertilizer given during planting had the best effect on rice growth and production; the longer the submergence period for rice variety, the higher the effect on rice growth and production.

Photosynthesis of amphibious and obligately submerged plants in CO2-rich lowland streams.

Science.gov (United States)

Sand-Jensen, Kaj; Frost-Christensen, Henning

1998-11-01

Small unshaded streams in lowland regions receive drainage water with high concentrations of free␣CO 2 , and they support an abundant growth of amphibious and obligately submerged plants. Our first objective was to measure the CO 2 regime during summer in a wide range of small alkaline Danish streams subject to wide variation in temperature, O 2 and CO 2 during the day. The second objective was to determine the effect of these variations on daily changes in light-saturated photosynthesis in water of a homophyllous and a heterophyllous amphibious species that only used CO 2 , and an obligately submerged species capable of using both HCO - 3 and CO 2 . We found that the median CO 2 concentrations of the streams were 11 and 6 times above air saturation in the morning and the afternoon, respectively, but stream sites with dense plant growth had CO 2 concentrations approaching air saturation in the afternoon. In contrast, outlets from lakes had low CO 2 concentrations close to, or below, air saturation. The amphibious species showed a reduction of photosynthesis in water from morning to afternoon along with the decline in CO 2 concentrations, while increasing temperature and O 2 had little effect on photosynthesis. Photosynthesis of the obligately submerged species varied little with the change of CO 2 because of HCO 3 - - use, and variations were mostly due to changes in O 2 concentration. Independent measurements showed that changes in temperature, O 2 and CO 2 could account for the daily variability of photosynthesis of all three species in water. The results imply that CO 2 supersaturation in small lowland streams is important for the rich representation of amphibious species and their contribution to system photosynthesis.

Risk spreading, habitat selection and division of biomass in a submerged clonal plant: Responses to heterogeneous copper pollution

International Nuclear Information System (INIS)

Yan, Xue; Wang, Haowen; Wang, Qingfeng; Rudstam, Lars G.

2013-01-01

Heterogeneity of contaminant-stress can be an important environmental factor for clonal plants. We focused on Cu transport among the clones, the foraging or fugitive behavior and biomass allocation of submerged plant, Vallisneria natans (Lour.) Hara, exposed to heterogeneous sediments. This study was carried out in aquatic mesocosms between March and September 2010. Cu accumulated in contaminated ramets was exported horizontally via stolons to other ramets in uncontaminated patches, and then transported both acropetally to leaves and basipetally to belowground structures. There was no indication that V. natans adopted morphological plasticity in response to heterogeneous contaminated habitat. In contrast to predictions, more biomass was allocated to belowground tissues in contaminated patches. We concluded that risk of Cu stress spread among submerged clones, and V. natans did not actively select habitat in contaminated patchy environment. Furthermore, V. natans adopted compensatory investments instead of division of labor to acquire nutrient and survive. -- Highlights: ► Response of submerged clonal plant in heterogeneous Cu soil was studied. ► Cu can spread among V. natans clones in contaminated patches. ► Ramets of V. natans grow randomly instead of habitat selection actively. ► Individual growth in patchy pollution was relative independent rather than DoL. -- Cu can spread among V. natans clones and the clones grow randomly and relative independent in heterogeneous Cu-contaminated sediment

Macroinvertebrates associated with two submerged macrophytes ...

African Journals Online (AJOL)

Macroinvertebrates associated with two submerged macrophytes, Lagarosiphon ilicifolius and Vallisneria aethiopica , in the Sanyati Basin, Lake Kariba, Zimbabwe: effect of plant morphological complexity.

A Survey of the Invasive Aquatic and Riparian Plants of the Lower Rio Grande

Science.gov (United States)

2005-04-01

monocultures in many areas. In 2001 and 2003, surveys were conducted starting below Amistad Reservoir to immediately below Falcon Reservoir to assess...management programs to inhibit further new infestations locally and downstream. In 2001, 20 sites on the Rio Grande River were surveyed from Amistad Reservoir...the 2001 survey, hydrilla was found in Amistad Reservoir and below Falcon Reservoir. In August 2002, hydrilla fragments were observed in plant

Biological Control Agents of Hydrilla Verticillata; Final Report on Surveys in East Africa, 1981-1984.

Science.gov (United States)

1986-07-01

vast numbers of chironomid larvae, together with small nematodes , trichopterans, and various other less abundant insect larvae. However, most of these...Luond, R. 1982. "A Revision of the Genus Hydrilla (Hydrocharitaceae)," Aquatic Botany, Vol 13, pp 485-504. Markham, R. H. 1982. "Search for Biocontrol

Leaf gas films contribute to rice (Oryza sativa) submergence tolerance during saline floods

DEFF Research Database (Denmark)

Herzog, Max; Konnerup, Dennis; Pedersen, Ole

2018-01-01

Floods and salinization of agricultural land adversely impact global rice production. We investigated whether gas films on leaves of submerged rice delay salt entry during saline submergence. Two-week-old plants with leaf gas films (+GF) or with gas films experimentally removed (-GF) were submerged...

Carbon-Flow-Based Modeling of Ecophysiological Processes and Biomass Dynamics of Submersed Aquatic Plants

National Research Council Canada - National Science Library

Best, Elly P. H; Boyd, William A

2007-01-01

...], Potamogeton pectinatus [POTAM], Hydrilla verticillata [HYDRIL], and Myriophyllum spicatum [MILFO]. These plant species are similar in growth strategy but differ significantly in morphology and physiology...

Modeling complex flow structures and drag around a submerged plant of varied posture

Science.gov (United States)

Boothroyd, Richard J.; Hardy, Richard J.; Warburton, Jeff; Marjoribanks, Timothy I.

2017-04-01

Although vegetation is present in many rivers, the bulk of past work concerned with modeling the influence of vegetation on flow has considered vegetation to be morphologically simple and has generally neglected the complexity of natural plants. Here we report on a combined flume and numerical model experiment which incorporates time-averaged plant posture, collected through terrestrial laser scanning, into a computational fluid dynamics model to predict flow around a submerged riparian plant. For three depth-limited flow conditions (Reynolds number = 65,000-110,000), plant dynamics were recorded through high-definition video imagery, and the numerical model was validated against flow velocities collected with an acoustic Doppler velocimeter. The plant morphology shows an 18% reduction in plant height and a 14% increase in plant length, compressing and reducing the volumetric canopy morphology as the Reynolds number increases. Plant shear layer turbulence is dominated by Kelvin-Helmholtz type vortices generated through shear instability, the frequency of which is estimated to be between 0.20 and 0.30 Hz, increasing with Reynolds number. These results demonstrate the significant effect that the complex morphology of natural plants has on in-stream drag, and allow a physically determined, species-dependent drag coefficient to be calculated. Given the importance of vegetation in river corridor management, the approach developed here demonstrates the necessity to account for plant motion when calculating vegetative resistance.

IODINE REMOVAL EFFICIENCY IN NON-SUBMERGED AND SUBMERGED SELF-PRIMING VENTURI SCRUBBER

Directory of Open Access Journals (Sweden)

MAJID ALI

2013-04-01

Full Text Available The objective of this conducted research is to study the iodine removal efficiency in a self-priming venturi scrubber for submerged and non-submerged operating conditions experimentally and theoretically. The alkaline solution is used as an absorbent, which is prepared by dissolving sodium hydroxide (NaOH and sodium thiosulphate (Na2S2O3 in water to remove the gaseous iodine (I2 from the gas. Iodine removal efficiency is examined at various gas flow rates and inlet concentrations of iodine for submerged and non-submerged operating conditions. In the non-submerged venturi scrubber, only the droplets take part in iodine removal efficiency. However, in a submerged venturi scrubber condition, the iodine gas is absorbed from gas to droplets inside the venturi scrubber and from bubbles to surrounding liquid at the outlet of a venturi scrubber. Experimentally, it is observed that the iodine removal efficiency is greater in the submerged venturi scrubber as compare to a non-submerged venturi scrubber condition. The highest iodine removal efficiency of 0.99±0.001 has been achieved in a submerged self-priming venturi scrubber condition. A mathematical correlation is used to predict the theoretical iodine removal efficiency in submerged and non-submerged conditions, and it is compared against the experimental results. The Wilkinson et al. correlation is used to predict the bubble diameter theoretically whereas the Nukiyama and Tanasawa correlation is used for droplet diameter. The mass transfer coefficient for the gas phase is calculated from the Steinberger and Treybal correlation. The calculated results for a submerged venturi scrubber agree well with experimental results but underpredicts in the case of the non-submerged venturi scrubber.

Iodine Removal Efficiency in Non-Submerged and Submerged Self-Priming Venturi Scrubber

Energy Technology Data Exchange (ETDEWEB)

Ali, Majid; Yan, Changqi; Sun, Zhongning; Gu, Haifeng; Wang, Junlong; Mehboob; Khurram [Harbin Engineering Univ., Harbin (China)

2013-04-15

The objective of this conducted research is to study the iodine removal efficiency in a self-priming venturi scrubber for submerged and non-submerged operating conditions experimentally and theoretically. The alkaline solution is used as an absorbent, which is prepared by dissolving sodium hydroxide (NaOH) and sodium thiosulphate (Na{sub 2}S{sub 2}O{sub 3}) in water to remove the gaseous iodine (I{sub 2}) from the gas. Iodine removal efficiency is examined at various gas flow rates and inlet concentrations of iodine for submerged and non-submerged operating conditions. In the non-submerged venturi scrubber, only the droplets take part in iodine removal efficiency. However, in a submerged venturi scrubber condition, the iodine gas is absorbed from gas to droplets inside the venturi scrubber and from bubbles to surrounding liquid at the outlet of a venturi scrubber. Experimentally, it is observed that the iodine removal efficiency is greater in the submerged venturi scrubber as compare to a non-submerged venturi scrubber condition. The highest iodine removal efficiency of 0.99±0.001 has been achieved in a submerged self-priming venturi scrubber condition. A mathematical correlation is used to predict the theoretical iodine removal efficiency in submerged and non-submerged conditions, and it is compared against the experimental results. The Wilkinson et al. correlation is used to predict the bubble diameter theoretically whereas the Nukiyama and Tanasawa correlation is used for droplet diameter. The mass transfer coefficient for the gas phase is calculated from the Steinberger and Treybal correlation. The calculated results for a submerged venturi scrubber agree well with experimental results but underpredicts in the case of the non-submerged venturi scrubber.

Iodine Removal Efficiency in Non-Submerged and Submerged Self-Priming Venturi Scrubber

International Nuclear Information System (INIS)

Ali, Majid; Yan, Changqi; Sun, Zhongning; Gu, Haifeng; Wang, Junlong; Mehboob; Khurram

2013-01-01

The objective of this conducted research is to study the iodine removal efficiency in a self-priming venturi scrubber for submerged and non-submerged operating conditions experimentally and theoretically. The alkaline solution is used as an absorbent, which is prepared by dissolving sodium hydroxide (NaOH) and sodium thiosulphate (Na 2 S 2 O 3 ) in water to remove the gaseous iodine (I 2 ) from the gas. Iodine removal efficiency is examined at various gas flow rates and inlet concentrations of iodine for submerged and non-submerged operating conditions. In the non-submerged venturi scrubber, only the droplets take part in iodine removal efficiency. However, in a submerged venturi scrubber condition, the iodine gas is absorbed from gas to droplets inside the venturi scrubber and from bubbles to surrounding liquid at the outlet of a venturi scrubber. Experimentally, it is observed that the iodine removal efficiency is greater in the submerged venturi scrubber as compare to a non-submerged venturi scrubber condition. The highest iodine removal efficiency of 0.99±0.001 has been achieved in a submerged self-priming venturi scrubber condition. A mathematical correlation is used to predict the theoretical iodine removal efficiency in submerged and non-submerged conditions, and it is compared against the experimental results. The Wilkinson et al. correlation is used to predict the bubble diameter theoretically whereas the Nukiyama and Tanasawa correlation is used for droplet diameter. The mass transfer coefficient for the gas phase is calculated from the Steinberger and Treybal correlation. The calculated results for a submerged venturi scrubber agree well with experimental results but underpredicts in the case of the non-submerged venturi scrubber

Waterlogging and submergence: surviving poor aeration

NARCIS (Netherlands)

Atwell, B.J.; Ismail, A.M.; Pedersen, O.; Shabala, S.; Sorrell, B.; Voesenek, Laurentius|info:eu-repo/dai/nl/074850849

2014-01-01

Flooding, resulting in soil waterlogging and in many situations even complete submergence of plants, is an important abiotic stress in many regions worldwide. The number of floods has increased in recent decades (Figure 18.1), and the severity of floods is expected to increase further in many

Hydrothermal processing of biomass from invasive aquatic plants

Science.gov (United States)

W. James Catallo; Todd F. Shupe; Thomas L. Eberhardt

2008-01-01

The purpose of this study was to examine the hydrothermal (HT) treatment of three invasive aquatic plants (i.e., Lemna sp., Hydrilla sp., and Eichhornia sp.) with respect to the generation of semi-volatile hydrocarbon product mixtures and biomass volume reduction. Identical HT treatments yielded similar semi-...

Multiple mitigation mechanisms: Effects of submerged plants on the toxicity of nine insecticides to aquatic animals.

Science.gov (United States)

Brogan, William R; Relyea, Rick A

2017-01-01

Understanding the processes that regulate contaminant impacts in nature is an increasingly important challenge. For insecticides in surface waters, the ability of aquatic plants to sorb, or bind, hydrophobic compounds has been identified as a primary mechanism by which toxicity can be mitigated (i.e. the sorption-based model). However, recent research shows that submerged plants can also rapidly mitigate the toxicity of the less hydrophobic insecticide malathion via alkaline hydrolysis (i.e. the hydrolysis-based model) driven by increased water pH resulting from photosynthesis. However, it is still unknown how generalizable these mitigation mechanisms are across the wide variety of insecticides applied today, and whether any general rules can be ascertained about which types of chemicals may be mitigated by each mechanism. We quantified the degree to which the submerged plant Elodea canadensis mitigated acute (48-h) toxicity to Daphnia magna using nine commonly applied insecticides spanning three chemical classes (carbamates: aldicarb, carbaryl, carbofuran; organophosphates: malathion, diazinon, chlorpyrifos; pyrethroids: permethrin, bifenthrin, lambda-cyhalothrin). We found that insecticides possessing either high octanol-water partition coefficients (log K ow ) values (i.e. pyrethroids) or high susceptibility to alkaline hydrolysis (i.e. carbamates and malathion) were all mitigated to some degree by E. canadensis, while the plant had no effect on insecticides possessing intermediate log K ow values and low susceptibility to hydrolysis (i.e. chlorpyrifos and diazinon). Our results provide the first general insights into which types of insecticides are likely to be mitigated by different mechanisms based on known chemical properties. We suggest that current models and mitigation strategies would be improved by the consideration of both mitigation models. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rhizoglomus melanum, a new arbuscular mycorrhizal fungal species associated with submerged plants in freshwater lake Avsjøen in Norway

Czech Academy of Sciences Publication Activity Database

Sudová, Radka; Sýkorová, Zuzana; Rydlová, Jana; Čtvrtlíková, Martina; Oehl, F.

2015-01-01

Roč. 14, č. 3 (2015), s. 1-8, no.9 ISSN 1617-416X R&D Projects: GA ČR GAP504/10/0781 Institutional support: RVO:67985939 ; RVO:60077344 Keywords : arbuscular mycorrhiza * biodiversity * submerged plants Subject RIV: EF - Botanics; DA - Hydrology ; Limnology (BC-A) Impact factor: 1.572, year: 2015

Improvement of Photosynthesis by Sub1 QTL in Rice Under Submergence: Probed by Chlorophyll Fluorescence OJIP Transients

Directory of Open Access Journals (Sweden)

Panda Debabrata

2011-09-01

Full Text Available The influence of submergence on the photosynthetic activity in rice plants either possessing or not possessing Sub1 QTL i.e. Swarna and Swarna Sub1 cultivars (cv. were evaluated under simulated complete submergence. The leaf photosynthetic rate and stomatal conductance decreased in both the cv. during the progression of submergence as compared to control plant but significant varietal differences was observed after 1 day (d of submergence. Submergence also alters the photo-system (PS II activity, as reflected in a decrease in the values of Fo, Fm and the Fv/Fm ratio and degradation of chlorophyll, more in Swarna than that of Swarna Sub1. Under complete submergence the shape of the OJIP transient also changed in rice leaves with decrease in maximal fluorescence (P=Fm intensity, resulted lowering of variable fluorescence levels. The decrease was more pronounced in Swarna compared to the Swarna Sub1 cv. Thus, Swarna Sub1 improves photosynthetic activity showing more photosynthetic rate compared to Swarna under submergence because, of less degradation of chlorophyll, higher stomatal conductance, and efficient PS II activity.

Culture Methodology for Experimental Investigations Involving Rooted Submersed Aquatic Plants.

Science.gov (United States)

1984-11-01

stolons or runners are best planted as intact plants (Sculthorpe 1967). Many species can be propagated from seed in addition to the above methods...J. 1984. Growth response of Myriophyllwm spicatu and Hydrilla verticillata when exposed to continuous, low concentrations of fluridone . Tech. Rept. A...aquatic plants, water, and bottom sediments. Weed Sci. 20:482-486. Sastroutomo, S. S. 1980. Dormancy and germination in axillary turions of iijiilZla

Plant pigment types, distributions, and influences on shallow water submerged aquatic vegetation mapping

Science.gov (United States)

Hall, Carlton R.; Bostater, Charles R., Jr.; Virnstein, Robert

2004-11-01

Development of robust protocols for use in mapping shallow water habitats using hyperspectral imagery requires knowledge of absorbing and scattering features present in the environment. These include, but are not limited to, water quality parameters, phytoplankton concentrations and species, submerged aquatic vegetation (SAV) species and densities, epiphytic growth on SAV, benthic microalgae and substrate reflectance characteristics. In the Indian River Lagoon, Fl. USA we conceptualize the system as having three possible basic layers, water column and SAV bed above the bottom. Each layer is occupied by plants with their associated light absorbing pigments that occur in varying proportions and concentrations. Phytoplankton communities are composed primarily of diatoms, dinoflagellates, and picoplanktonic cyanobacteria. SAV beds, including flowering plants and green, red, and brown macro-algae exist along density gradients ranging in coverage from 0-100%. SAV beds may be monotypic, or more typically, mixtures of the several species that may or may not be covered in epiphytes. Shallow water benthic substrates are colonized by periphyton communities that include diatoms, dinoflagellates, chlorophytes and cyanobacteria. Inflection spectra created form ASIA hyperspectral data display a combination of features related to water and select plant pigment absorption peaks.

Ash characteristics and plant nutrients in some aquatic biomasses

Science.gov (United States)

Masto, Reginald; Pandit, Ankita; George, Joshy; Mukhopadhyay, Sangeeta; Selvi, Vetrivel; Ram, Lal

2016-04-01

Aquatic biomasses are explored as potential fuel source for direct combustion because of their faster growth and no land requirement. The energy density and the ash characteristics of the aquatic biomasses are to be evaluated for their suitability for energy extraction. In the study, four aquatic plant samples namely Eichornia crassipes, Hydrilla verticilleta, Lemna minor, Spirogyra spp were collected from a pond in Digwadih Campus of Central Institute of Mining and Fuel Research, Dhanbad. The biomasses were air dried, powdered and ashed at different temperatures. Volatile C was relatively lower in Spirogyra and Hydrilla (53 %) than Eichornia (62.6 %) or Lemna (59.7 %), whereas fixed C was higher for Eichornia and Lemna (about 10 %) and lower for Hydrilla (1 %). Ultimate analysis showed that the carbon content was in the order Eichornia > Lemna > Spirogyra > Hydrilla. The IR spectra of each raw biomass is compared to their respective ashes obtained at different temperatures (500-900°C). With increase in ashing temperature from 500-900°C there is gradual breakdown of the cellulosic structure hence, peaks around 2900-2800cm-1 caused by aliphatic C-H vibration tends to disappear slowly in ash. More number of peaks appears at lower wavenumbers in ashes of all the biomass samples indicating towards increased percentage of inorganic ion species. Considerable enrichment of SiO2 is validated with prominent peaks at 1100-900 cm-1 in all the ashes. Lemna and Spirogyra has a similar ash composition (Si > Al > Ca > K), whereas, Ca was higher in Hydrilla (Si > Ca > K > Al). Eichornia (Si > K > Ca > Al) has higher K and Ca than Al. SiO2 and Al2O3 were higher in Spirogyra, while SiO2 and CaO in Eichornia and Hydrilla. K first increased from 500-700/800⁰C, and then decreased from 800-900⁰C. Cl is lost slowly in ash from 500-700/800⁰C and then by a drastic reduction from 800-900⁰C. S is enhanced in ash at all temperatures although the change is quite small. Most of the Cl

Mesohaline submerged aquatic vegetation survey along the U.S. gulf of Mexico coast, 2001 and 2002: A salinity gradient approach

Science.gov (United States)

Merino, J.H.; Carter, J.; Merino, S.L.

2009-01-01

Distribution of marine submerged aquatic vegetation (SAV; i.e., seagrass) in the northern Gulf of Mexico coast has been documented, but there are nonmarine submersed or SAV species occurring in estuarine salinities that have not been extensively reported. We sampled 276 SAV beds along the gulf coast in Florida, Alabama, Mississippi, Louisiana, and Texas in 2001 and 2002 in oligohaline to polyhaline (0 to 36 parts per thousand) waters to determine estuarine SAV species distribution and identify mesohaline SAV communities. A total of 20 SAV and algal species was identified and habitat characteristics such as salinity, water depth, pH, conductivity, turbidity, dissolved oxygen, and sediment composition were collected. Fourteen SAV species occurred two or more times in our samples. The most frequently occurring species was Ruppia maritima L. (n = 148), occurring in over half of SAV beds sampled. Eleocharis sp. (n = 47), characterized with an emergent rather than submerged growth form, was a common genus in the SAV beds sampled. A common marine species was Halodule wrightii Asch. (n = 36). Nonindigenous species Myriophyllum spicatum L. (n = 31) and Hydrilla verticillata (L. f.) Royle (n = 6) were present only in oligohaline water. Analyzing species occurrence and environmental characteristics using canonical correspondence and two-way indicator species analysis, we identify five species assemblages distinguished primarily by salinity and depth. Our survey increases awareness of nonmarine SAV as a natural resource in the gulf, and provides baseline data for future research. ?? 2009 by the Marine Environmental Sciences Consortium of Alabama.

Characteristics and kinetic studies of Hydrilla verticillata pyrolysis via thermogravimetric analysis.

Science.gov (United States)

Hu, Zhiquan; Chen, Zhihua; Li, Genbao; Chen, Xiaojuan; Hu, Mian; Laghari, Mahmood; Wang, Xun; Guo, Dabin

2015-10-01

The pyrolysis characteristics and kinetic of Hydrilla verticillata (HV) have been investigated using non-isothermal thermogravimetric analysis. The results showed that the pyrolysis behavior of HV can be divided into two independent stages. The kinetics of Stage I was investigated using a distributed activation energy model (DAEM) with discrete 99 first-order reactions. Stage II was an independent stage which corresponds to the decomposition of calcium oxalate, whose kinetics was studied using iso-conversional method together with compensation effect and master-plots method. The activation energies ranged from 92.39 to 506.17 and 190.42 to 222.48 kJ/mol for the first and second stages respectively. Calculated data gave very good fit to the experimental data. Copyright © 2015 Elsevier Ltd. All rights reserved.

Responses of bacterial community structure and denitrifying bacteria in biofilm to submerged macrophytes and nitrate

Science.gov (United States)

Zhang, Songhe; Pang, Si; Wang, Peifang; Wang, Chao; Guo, Chuan; Addo, Felix Gyawu; Li, Yi

2016-10-01

Submerged macrophytes play important roles in constructed wetlands and natural water bodies, as these organisms remove nutrients and provide large surfaces for biofilms, which are beneficial for nitrogen removal, particularly from submerged macrophyte-dominated water columns. However, information on the responses of biofilms to submerged macrophytes and nitrogen molecules is limited. In the present study, bacterial community structure and denitrifiers were investigated in biofilms on the leaves of four submerged macrophytes and artificial plants exposed to two nitrate concentrations. The biofilm cells were evenly distributed on artificial plants but appeared in microcolonies on the surfaces of submerged macrophytes. Proteobacteria was the most abundant phylum in all samples, accounting for 27.3-64.8% of the high-quality bacterial reads, followed by Chloroflexi (3.7-25.4%), Firmicutes (3.0-20.1%), Acidobacteria (2.7-15.7%), Actinobacteria (2.2-8.7%), Bacteroidetes (0.5-9.7%), and Verrucomicrobia (2.4-5.2%). Cluster analysis showed that bacterial community structure can be significantly different on macrophytes versus from those on artificial plants. Redundancy analysis showed that electrical conductivity and nitrate concentration were positively correlated with Shannon index and operational taxonomic unit (OTU) richness (log10 transformed) but somewhat negatively correlated with microbial density. The relative abundances of five denitrifying genes were positively correlated with nitrate concentration and electrical conductivity but negatively correlated with dissolved oxygen.

Underwater photosynthesis and respiration in leaves of submerged wetland plants: gas films improve CO2 and O2 exchange

DEFF Research Database (Denmark)

Colmer, Timothy David; Pedersen, Ole

2007-01-01

(N) was enhanced up to sixfold. Gas films on submerged leaves enable continued gas exchange via stomata and thus bypassing of cuticle resistance, enhancing exchange of O(2) and CO(2) with the surrounding water, and therefore underwater P(N) and respiration.......Many wetland plants have gas films on submerged leaf surfaces. We tested the hypotheses that leaf gas films enhance CO(2) uptake for net photosynthesis (P(N)) during light periods, and enhance O(2) uptake for respiration during dark periods. Leaves of four wetland species that form gas films......, and two species that do not, were used. Gas films were also experimentally removed by brushing with 0.05% (v/v) Triton X. Net O(2) production in light, or O(2) consumption in darkness, was measured at various CO(2) and O(2) concentrations. When gas films were removed, O(2) uptake in darkness was already...

Over-expression of Sub1 A, a submergence tolerance gene from ...

African Journals Online (AJOL)

Sub1A, an ethylene-response-factor-like (ERE-like) gene, mediates the extinguished submergence tolerance of rice. To gain further insight into the function of Sub1A in other species, we transformed tobacco plants with the gene under the control of the ubiquitin promoter. Compared to the wild-type plants, transgenic plants ...

Association of Candidate Genes With Submergence Response in Perennial Ryegrass

Directory of Open Access Journals (Sweden)

Xicheng Wang

2017-05-01

Full Text Available Perennial ryegrass is a popular cool-season grass species due to its high quality for forage and turf. The objective of this study was to identify associations of candidate genes with growth and physiological traits to submergence stress and recovery after de-submergence in a global collection of 94 perennial ryegrass accessions. Accessions varied largely in leaf color, plant height (HT, leaf fresh weight (LFW, leaf dry weight (LDW, and chlorophyll fluorescence (Fv/Fm at 7 days of submergence and in HT, LFW and LDW at 7 days of recovery in two experiments. Among 26 candidate genes tested by various models, single nucleotide polymorphisms (SNPs in 10 genes showed significant associations with traits including 16 associations for control, 10 for submergence, and 8 for recovery. Under submergence, Lp1-SST encoding sucrose:sucrose 1-fructosyltransferase and LpGA20ox encoding gibberellin 20-oxidase were associated with LFW and LDW, and LpACO1 encoding 1-aminocyclopropane-1-carboxylic acid oxidase was associated with LFW. Associations between Lp1-SST and HT, Lp6G-FFT encoding fructan:fructan 6G-fructosyltransferase and Fv/Fm, LpCAT encoding catalase and HT were also detected under submergence stress. Upon de-submergence, Lp1-SST, Lp6G-FFT, and LpPIP1 encoding plasma membrane intrinsic protein type 1 were associated with LFW or LDW, while LpCBF1b encoding C-repeat binding factor were associated with HT. Nine significant SNPs in Lp1-SST, Lp6G-FFT, LpCAT, and LpACO1 resulted in amino acid changes with five substitutions found in Lp1-SST under submergence or recovery. The results indicated that allelic diversity in genes involved in carbohydrate and antioxidant metabolism, ethylene and gibberellin biosynthesis, and transcript factor could contribute to growth variations in perennial ryegrass under submergence stress and recovery after de-submergence.

Oxygen dynamics during submergence in the halophytic stem succulent Halosarcia pergranulata

DEFF Research Database (Denmark)

Pedersen, Ole; Vos, Harrie; Colmer, Timothy David

2006-01-01

This study elucidated O2 dynamics in shoots and roots of submerged Halosarcia pergranulata (Salicornioideae), a perennial halophytic stem succulent that grows on flood-prone mudflats of salt lakes. Oxygen within shoots and roots was measured using microelectrodes, for plants when waterlogged...... the roots, at least during the first several hours (the time period measured) after submergence or when light periods followed darkness. The influence of light on tissue O2 dynamics was confirmed in an experiment on a submerged plant in a salt lake in south-western Australia. In the late afternoon, partial...... pressure of O2 (pO2) in the succulent stem was 23.2 kPa (i.e. ~10% above that in the air), while in the roots, it was 6.2-9.8 kPa. Upon sunset, the pO2 in the succulent stems declined within 1 h to below detection, but then showed some fluctuations with the pO2 increasing to at most 2.5 kPa during...

Effect of submergence-emergence sequence and organic matter or aluminosilicate amendment on metal uptake by woody wetland plant species from contaminated sediments

International Nuclear Information System (INIS)

Vandecasteele, Bart; Du Laing, Gijs; Tack, Filip M.G.

2007-01-01

Site-specific hydrological conditions affect the availability of trace metals for vegetation. In a greenhouse experiment, the effect of submersion on the metal uptake by the wetland plant species Salix cinerea and Populus nigra grown on a contaminated dredged sediment-derived soil and on an uncontaminated soil was evaluated. An upland hydrological regime for the polluted sediment caused elevated Cd concentrations in leaves and cuttings for both species. Emergence and soil oxidation after initial submersion of a polluted sediment resulted in comparable foliar Cd and Zn concentrations for S. cinerea as for the constant upland treatment. The foliar Cd and Zn concentrations were clearly higher than for submerged soils after initial upland conditions. These results point at the importance of submergence-emergence sequence for plant metal availability. The addition of foliar-based organic matter or aluminosilicates to the polluted sediment-derived soil in upland conditions did not decrease Cd and Zn uptake by S. cinerea. - The effect of a wetland hydrological regime on Cd uptake was similar for Populus nigra and Salix cinerea

Production of tannase through submerged fermentation of tannin-containing plant extracts by Bacillus licheniformis KBR6.

Science.gov (United States)

Das Mohapatra, Pradeep K; Mondal, Keshab C; Pati, Bikas R

2006-01-01

Tannins are water-soluble polyphenolic compounds found in plants as secondary metabolites. The presence of these substances in the barks of eight different plants was initially examined and their crude extracts were used separately as a substrate for production of tannase through submerged fermentation by Bacillus licheniformis KBR6. Tannase production as well as biodegradation of the substrate reached a maximum within 15 to 18 h against crude tannin extract obtained from Anacardium occidentale. Among different concentrations of the crude tannin tested, 0.5% (w/v) induced maximum synthesis of enzyme. Tannase production was higher by almost two-fold in the presence of crude tannin compared to pure tannic acid used as a substrate. It seems that industrial production of tannase, using bark extract of A. occidentale can be a very simple and suitable alternative to presently used procedures.

State of South Carolina Cooperative Aquatic Plant Control Program.

Science.gov (United States)

1980-11-01

of a diquat and copper sulfate pentahydrate herbicide combination for hydrilla control was carried out by Yeo et. al. (1974). The copper was applied at...effective combination to control egeria and hydrilla (Gangstad, 1976). A diquat- copper sulfate combination is more effective in controlling hydrilla than the... copper resulting from the use of algacides or herbicides basic copper carbonate (malachite), copper sulfate , and copper tri- ethanolamine to control

Tolerance of combined submergence and salinity in the halophytic stem-succulent Tecticornia pergranulata

DEFF Research Database (Denmark)

Colmer, T D; Vos, H; Pedersen, Ole

2009-01-01

pergranulata subsp. pergranulata (syn. Halosarcia pergranulata subsp. pergranulata). Growth and total sugars in succulent stems were assessed as a function of time after submergence. Underwater net photosynthesis, dark respiration, total sugars, glycinebetaine, Na(+), Cl(-) and K(+), in succulent stems, were...... assessed in a NaCl dose-response experiment. KEY RESULTS: Submerged plants ceased to grow, and tissue sugars declined. Photosynthesis by succulent stems was reduced markedly when underwater, as compared with in air. Capacity for underwater net photosynthesis (P(N)) was not affected by 10-400 mM Na......Cl, but it was reduced by 30 % at 800 mM. Dark respiration, underwater, increased in succulent stems at 200-800 mM NaCl, as compared with those at 10 mM NaCl. On an ethanol-insoluble dry mass basis, K(+) concentration in succulent stems of submerged plants was equal to that in drained controls, across all Na...

Exploring the Spatial-Seasonal Dynamics of Water Quality, Submerged Aquatic Plants and Their Influencing Factors in Different Areas of a Lake

Directory of Open Access Journals (Sweden)

Kun Li

2017-09-01

Full Text Available The degradation of water quality in lakes and its negative effects on freshwater ecosystems have become a serious problem worldwide. Exploring the dynamics in the associated factors is essential for water pollution management and control. GIS interpolation, principal component analysis (PCA and multivariate statistical techniques were used to identify the main pollution sources in different areas of Honghu Lake. The results indicate that the spatial distribution of the concentrations of total nitrogen (TN, total phosphate (TP, ammonia nitrogen (NH4+–N, and permanganate index (CODMn have similar characteristics and that their values gradually increased from south to north during the three seasons in Honghu Lake. The major influencing factors of water quality varied across the different areas and seasons. The relatively high concentrations of TN and TP, which might limit the growth of submerged aquatic plants, were mainly caused by anthropogenic factors. Our work suggests that spatial analyses combined with PCA are useful for investigating the factors that influence water quality and submerged aquatic plant biomass in different areas of a lake. These findings provide sound information for the future water quality management of the lake or even the entire lake basin.

Microcystin production in epiphytic cyanobacteria on submerged macrophytes.

Science.gov (United States)

Mohamed, Zakaria A; Al Shehri, Abdulrahman M

2010-06-15

Cyanotoxins have been largely studied in planktonic and benthic cyanobacteria, but microcystin (MCYST) production in epiphytic cyanobacteria has not been reported yet. The present study reports for the first time the MCYST production in epiphytic cyanobacteria on submerged macrophytes. During this study, four common submerged macrophytes in eutrophic pond in Saudi Arabia were surveyed for the presence of toxic epiphytic cyanobacteria. The results showed that chlorophyll-a and total biovolume of epiphytic cyanobacteria differed significantly among submerged plants with highest values obtained in Stratiotes aloides and lowest in Elodea canadensis. Epiphytic materials collected from Ceratophyllum demersum and S. aloides had higher species diversities than materials collected from E. canadensis and Myriophyllum verticillatum. The cyanobacteria, Merismopedia tenuissima and Leptolyngbya boryana were recorded with a high abundance in epiphytic materials collected from all submerged macrohpytes. Based on Enzyme-linked immunosorbent assay (ELISA), these two species were found to produce MCYSTs (MCYSTs) with concentrations of 1438 and 630 microg g(-1) dry weight, respectively. HPLC analysis of the methanolic extracts of the two species showed that M. tenuissima extract contained MCYST-RR and -LR/demethyl LR plus 3 minor unidentified MCYSTs, while L. boryana extract contained MCYST-YR, -LR/demethyl LR, and 2 minor unidentified MCYSTs. This study suggests that epiphytic species should be considered during monitoring of toxic cyanobacteria in water sources. 2010 Elsevier Ltd. All rights reserved.

Leaf gas films delay salt entry and enhance underwater photosynthesis and internal aeration of Melilotus siculus submerged in saline water

DEFF Research Database (Denmark)

Teakle, Natasha Lea; Colmer, Timothy David; Pedersen, Ole

2014-01-01

A combination of flooding and salinity is detrimental to most plants. We studied tolerance of complete submergence in saline water for Melilotus siculus, an annual legume with superhydrophobic leaf surfaces that retain gas films when under water. M. siculus survived complete submergence of 1 week...... at low salinity (up to 50 mol m(-3) NaCl), but did not recover following de-submergence from 100 mol m(-3) NaCl. The leaf gas films protected against direct salt ingress into the leaves when submerged in saline water, enabling underwater photosynthesis even after 3 d of complete submergence. By contrast......, leaves with the gas films experimentally removed suffered from substantial Na(+) and Cl(-) intrusion and lost the capacity for underwater photosynthesis. Similarly, plants in saline water and without gas films lost more K(+) than those with intact gas films. This study has demonstrated that leaf gas...

Use of phosphorus to alleviate stress induced by cadmium and zinc ...

African Journals Online (AJOL)

The potential mechanism by which P antagonizes the toxicity of Zn and Cd was investigated in Elodea nuttallii and Hydrilla verticillata to understand the interactions between P, Cd and Zn pollutants. The two submerged macrophytes were treated with a combination of Cd (0.25 mg L-1) and Zn (1.0 mg L-1) and various ...

Dimensioning of activation systems using submerged membranes at municipal sewage treatment plants; Bemessung von Membranbelebungsanlagen beim Einsatz zur Reinigung kommunaler Abwaesser

Energy Technology Data Exchange (ETDEWEB)

Ohle, P.; Dorgeloh, E. [Technische Hochschule Aachen (DE). Inst. fuer Siedlungswasserwirtschaft (ISA)

1999-07-01

Dimensioning of conventional activation systems in Germany as a rule relies on instruction sheet A131 of the Abwassertechnische Vereinigung or follows the Hochschulgruppen approach (HSG). They contain recommendations as to the size of the nitrification and denitrification zones, the amount of oxygen supplied and sludge production, and the size of the final sedimentation tank. For the use of sludge activation techniques by means of submerged membranes at municipal sewage treatment plant there so far do not exist any clues to dimensioning that make allowance for the modified boundary conditions. The present paper analyses instruction sheet A131 for its suitability as a basis in the dimensioning of sludge activation systems with submerged membranes at municipal sewage treatment plant. Then the dimensioning instructions are modified to suit the changed boundary conditions, and recommendations for the dimensioning of activation systems with submerged membranes on the basis of extensive studies carried out at the Institut fuer Siedlungswasserwirtschaft ISA of Aachen Technical University RWTH are given. (orig.) [German] Die Bemessung konventioneller Belebungsverfahren erfolgt in Deutschland i.d.R. auf der Grundlage des Arbeitsblatts A 131 der Abwassertechnischen Vereinigung bzw. nach dem Hochschulgruppenansatz (HSG). Sie enthalten Empfehlungen bezueglich der Dimensionierung von Nitrifikations- und Denitrifikationszone, Sauerstoffversorgung, Schlammproduktion und Nachklaerbecken. Fuer den Einsatz von Membranbelebungsanlagen in kommunalen Klaeranlagen existieren bislang keine Bemessungshinweise, die den veraenderten Randbedingungen Rechnung tragen. Der vorliegende Beitrag analysiert das Arbeitsblatt A 131 in Hinsicht auf die Moeglichkeit zur Anwendung fuer die Bemessung von Membranbelebungsanlagen beim Einsatz zur kommunalen Abwasserreinigung. Im Weiteren erfolgt die Modifikation der Bemessungshinweise hinsichtlich der geaenderten Randbedingungen und die Angabe von

US State Submerged Lands

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Submerged Lands Act (43 U.S.C. Section 1301 et seq.) grants coastal states title to natural resources located within their coastal submerged lands and navigable...

The influences of sugars and plant growth regulators on β-glucan synthesis of G. lucidum mycelium in submerged culture

Science.gov (United States)

Thao, Cao Phuong; Tien, Le Thi Thuy

2017-09-01

β - glucan is intracellular polysaccharide (IPS), extracted from Ganoderma lucidum mycelium that can enhance human immune respond. This study aimed to stimulate the production of β - glucan in G. lucidum mycelium through optimating the carbonhydrates and plant rowth regulators in submerged culture. The results showed that the stimulation or inhibition of IPS production as well as β - glucan biosynthesis could be adjusted depend on the type and concentration of carbonhydrates and plant growth regulators. The supplement of lactose 80 g/L and BA 1 mg/L in medium could cause the highest IPS production (644.478 mg/g DW) and β - glucan increased up to 0.15/DW, that raised twice as much as without plant growth regulators. Futhermore, the optimation of other environmental elements were figured out were completely dark and 150 rpm on rotary shaker. This result could be used as premise for production of β - glucan in pilot.

Submerged Medium Voltage Cable Systems at Nuclear Power Plants. A Review of Research Efforts Relevant to Aging Mechanisms and Condition Monitoring

Energy Technology Data Exchange (ETDEWEB)

Brown, Jason [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bernstein, Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); White, II, Gregory Von [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Glover, Steven F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Neely, Jason C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pena, Gary [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Williamson, Kenneth Martin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Zutavern, Fred J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gelbard, Fred [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-03-01

and industrial literature was performed to identify : 1) findings regarding the degradation mechanisms of submerged cabling and 2) condition monitoring methods that may prove useful in predict ing the remaining lifetime of submerged medium voltage p ower cables . The re search was conducted by a multi - disciplinary team , and s ources includ ed official NRC reports, n ational l aboratory reports , IEEE standards, conference and journal proceedings , magazine articles , PhD dissertations , and discussions with experts . The purpose of this work was to establish the current state - of - the - art in material degradation modeling and cable condition monitoring techniques and to identify research gaps . Subsequently, future areas of focus are recommended to address these research gaps and thus strengthen the efficacy of the NRC's developing cable condition monitoring program . Results of this literature review and details of the test ing recommendations are presented in this report . FOREWORD To ensure the safe, re liable, and cost - effective long - term operation of nuclear power plants, many systems, structures, and components must be continuously evaluated. The Nuclear Regulatory Commission (NRC) has identified that cables in submerged environments are of concern, particularly as plants are seeking license renewal. To date, there is a lack of consensus on aging and degradation mechanisms even though the area of submerged cables has been extensively studied. Consequently, the ability to make lifetime predictions for submerged cable does not yet exist. The NRC has engaged Sandia National Laboratories (SNL) to lead a coordinated effort to help elucidate the aging and degradation of cables in submerged environments by collaborating with cable manufacturers, utilities, universities, and other government agencies. A team of SNL experts was assembled from the laboratories including electrical condition monitoring, mat erial science, polymer degradation, plasma physics

Identification of the submergence tolerance QTL Come Quick Drowning1 (CGD1) in Arabidopsis thaliana

NARCIS (Netherlands)

Akman, Melis; Kleine, Rogier; Tienderen, van Peter H.; Schranz, Eric M.

2017-01-01

Global climate change is predicted to increase water precipitation fluctuations and lead to localized prolonged floods in agricultural fields and natural plant communities. Thus, understanding the genetic basis of submergence tolerance is crucial in order to improve plant survival under these

The mechanism of improved aeration due to gas films on leaves of submerged rice.

Science.gov (United States)

Verboven, Pieter; Pedersen, Ole; Ho, Quang Tri; Nicolai, Bart M; Colmer, Timothy D

2014-10-01

Some terrestrial wetland plants, such as rice, have super-hydrophobic leaf surfaces which retain a gas film when submerged. O2 movement through the diffusive boundary layer (DBL) of floodwater, gas film and stomata into leaf mesophyll was explored by means of a reaction-diffusion model that was solved in a three-dimensional leaf anatomy model. The anatomy and dark respiration of leaves of rice (Oryza sativa L.) were measured and used to compute O2 fluxes and partial pressure of O2 (pO2 ) in the DBL, gas film and leaf when submerged. The effects of floodwater pO2 , DBL thickness, cuticle permeability, presence of gas film and stomatal opening were explored. Under O2 -limiting conditions of the bulk water (pO2  gas film significantly increases the O2 flux into submerged leaves regardless of whether stomata are fully or partly open. With a gas film, tissue pO2 substantially increases, even for the slightest stomatal opening, but not when stomata are completely closed. The effect of gas films increases with decreasing cuticle permeability. O2 flux and tissue pO2 decrease with increasing DBL thickness. The present modelling analysis provides a mechanistic understanding of how leaf gas films facilitate O2 entry into submerged plants. © 2014 John Wiley & Sons Ltd.

Surviving floods: leaf gas films improve O₂ and CO₂ exchange, root aeration, and growth of completely submerged rice

DEFF Research Database (Denmark)

Pedersen, Ole; Rich, Sarah Meghan; Colmer, Timothy David

2009-01-01

When completely submerged, the leaves of some species retain a surface gas film. Leaf gas films on submerged plants have recently been termed 'plant plastrons', analogous with the plastrons of aquatic insects. In aquatic insects, surface gas layers (i.e. plastrons) enlarge the gas–water interface...... or when in light, was improved considerably when leaf gas films were present. Thus, leaf gas films contribute to the submergence tolerance of rice, in addition to those traits already recognized, such as the shoot-elongation response, aerenchyma and metabolic adjustments to O2 deficiency and oxidative...... stress....

Root transcript profiling of two Rorippa (brassicaceae) species reveals gene clusters associated with extreme submergence tolerance.

NARCIS (Netherlands)

Sasidharan, R.; Mustroph, A.; Boonman, A.; Akman, M.; Ammerlaan, A.M.H.; Breit, T.M.; Schranz, M.E.; Voesenek, L.A.C.J.; Tienderen, van P.H.

2013-01-01

Complete submergence represses photosynthesis and aerobic respiration, causing rapid mortality in most terrestrial plants. However, some plants have evolved traits allowing them to survive prolonged flooding, such as species of the genus Rorippa, close relatives of Arabidopsis (Arabidopsis

Antioxidant activity of seedling growth in selected soybean genotypes (Glycine max (L.) Merrill) responses of submergence

Science.gov (United States)

Damanik, R. I.; Marbun, P.; Sihombing, L.

2016-08-01

In order to better understand the physiological and biochemical responses relating to direct seeding establishment in soybeans, the plant growth rate and antioxidative defense responses of seedlings in seven Indonesian soybean genotypes (Anjasmoro, Detam-1, Detam-2, Dieng, Grobogan, Tanggamus, and Willis) at different submergence periods (4, and 8 days) were examined. Twelve-day old seedlings were hydroponically grown in limited oxygen conditions. The results showed that the chlorophyll content in soybean seedlings was reduced beginning as early as 4 d under submerged condition, except for Detam-1, Detam-2, and Grobogan genotypes. The dry weight and protein concentration of seedlings were significantly higher at control condition (0 d) than those in submerged condition. The activities of superoxide dismutase (SOD) increased linearly until 8 d submerged for all genotypes. On the other hand, our results showed that catalase (CAT) and ascorbate peroxidase (APX) activities did not work together, meaning that CAT is activated and APX deactivated, or vice versa, in response to submergence conditions, except for Grobogan and Tanggamus genotypes which had an effect on both CAT and APX activities. Submergence stress led to a significant increase in glutathione reductase (GR) together with APX activity for Detam-2 and Dieng genotypes at 8 d submerged.

Microdistribution of 241Am in structures of submerged macrophyte Elodea canadensis growing in the Yenisei River

International Nuclear Information System (INIS)

Bondareva, L.; Vlasova, I.; Mogilnaya, O.; Bolsunovsky, A.; Kalmykov, S.

2010-01-01

A submerged macrophyte of the Yenisei River, Elodea canadensis, was used to study the microdistribution of the artificial radionuclide 241 Am among different components of the plant. The total amount of 241 Am added to the experimental system was 1850 ± 31 Bq/L. The total amount of 241 Am accumulated by the plants was 182 Bq per sample, or 758,333 ± 385 Bq/kg dry mass. It has been found that the major portion of 241 Am accumulated by E. canadensis, up to 85%, was bound to solid components of the cells. It is observed that the microdistribution of 241 Am within different components of the submerged plant E. canadensis was not uniform. 241 Am distribution vary depending on the age of the leaf blades, the state of the cells and morphological features of the plant stem.

Microdistribution of 241Am in structures of submerged macrophyte Elodea canadensis growing in the Yenisei River.

Science.gov (United States)

Bondareva, L; Vlasova, I; Mogilnaya, O; Bolsunovsky, A; Kalmykov, S

2010-01-01

A submerged macrophyte of the Yenisei River, Elodea canadensis, was used to study the microdistribution of the artificial radionuclide (241)Am among different components of the plant. The total amount of (241)Am added to the experimental system was 1850+/-31 Bq/L. The total amount of (241)Am accumulated by the plants was 182 Bq per sample, or 758,333+/-385 Bq/kg dry mass. It has been found that the major portion of (241)Am accumulated by E. canadensis, up to 85%, was bound to solid components of the cells. It is observed that the microdistribution of (241)Am within different components of the submerged plant E. canadensis was not uniform. (241)Am distribution vary depending on the age of the leaf blades, the state of the cells and morphological features of the plant stem.

Photosynthetic consequences of phenotypic plasticity in response to submergence: Rumex palustris as a case study

NARCIS (Netherlands)

Mommer, L.; Pons, T.L.; Visser, E.J.W.

2006-01-01

Survival and growth of terrestrial plants is negatively affected by complete submergence. This is mainly the result of hampered gas exchange between plants and their environment, since gas diffusion is severely reduced in water compared with air, resulting in O2 deficits which limit aerobic

Mineralization of surfactants by the microbiota of submerged plant detritus.

Science.gov (United States)

Federle, T W; Ventullo, R M

1990-02-01

In wetlands and canopied bodies of water, plant detritus is an important source of carbon and energy. Detrital materials possess a large surface area for sorption of dissolved organics and are colonized by a large and diverse microbiota. To examine the biodegradation of surfactants by these microorganisms, submerged oak leaves were obtained from a laundromat wastewater pond, its overflow, and a pristine control pond. Leaves were cut into disks and incubated in sterile water amended with 50 mug of C-labeled linear alkylbenzene sulfonate (LAS), linear alcohol ethoxylate, stearyltrimethyl ammonium chloride, distearyldimethyl ammonium chloride, benzoic acid, or mixed amino acids per liter. Sorption of the test compounds to the detritus and evolution of CO(2) were followed with time. All of the compounds sorbed to the detritus to various degrees, with LAS and stearyltrimethyl ammonium chloride the most sorptive and benzoic acid the least. All compounds were mineralized without a lag. With leaves from the laundromat wastewater pond, half-lives were 12.6 days for LAS, 8.4 days for linear alcohol ethoxylate, 14.2 days for stearyltrimethyl ammonium chloride, 1.0 days for benzoic acid, and 2.7 days for mixed amino acids. Mineralization of LAS and linear alcohol ethoxylate by control pond leaves was slower and exhibited an S-shaped rather than a typical first-order pattern. This study shows that detritus represents a significant site of surfactant removal in detritus-rich systems.

Mineralization of surfactants by the microbiota of submerged plant detritus

International Nuclear Information System (INIS)

Federle, T.W.; Ventullo, R.M.

1990-01-01

In wetlands and canopied bodies of water, plant detritus is an important source of carbon and energy. Detrital materials possess a large surface area for sorption of dissolved organics and are colonized by a large and diverse microbiota. To examine the biodegradation of surfactants by these microorganisms, submerged oak leaves were obtained from a laundromat wastewater pond, its overflow, and a pristine control pond. Leaves were cut into disks and incubated in sterile water amended with 50 μg of 14 C-labeled linear alkylbenzene sulfonate (LAS), linear alcohol ethoxylate, stearyltrimethyl ammonium chloride, distearyldimethyl ammonium chloride, benzoic acid, or mixed amino acids per liter. Sorption of the test compounds to the detritus and evolution of 14 CO 2 were followed with time. All of the compounds sorbed to the detritus to various degrees, with LAS and stearyltrimethyl ammonium chloride the most sorptive and benzoic acid the least. All compounds were mineralized without a lag. With leaves from the laundromat wastewater pond, half-lives were 12.6 days for LAS, 8.4 days for linear alcohol ethoxylate, 14.2 days for stearyltrimethyl ammonium chloride, 1.0 days for benzoic acid, and 2.7 days for mixed amino acids. Mineralization of LAS and linear alcohol ethoxylate by control pond leaves was slower and exhibited an S-shaped rather than a typical first-order pattern. This study shows that detritus represents a significant site of surfactant removal in detritus-rich systems

Molecular characterization of the submergence response of Arabidopsis thaliana ecotype Columbia

DEFF Research Database (Denmark)

Lee, S.C.; Mustroph, A.; Sasidaharan, R.

2011-01-01

partial pressure of the petiole and root had stabilized at c. 6 and 0.1 kPa, respectively. As controls, plants were untreated or exposed to darkness. Following quantitative profiling of cellular mRNAs with the Affymetrix ATH1 platform, changes in the transcriptome in response to submergence, early...... darkness, and O2-deprivation were evaluated by fuzzy k-means clustering. This identified genes co-regulated at the conditional, developmental or organ-specific level. Mutants for 10 differentially expressed HYPOXIA-RESPONSIVE UNKNOWN PROTEIN (HUP) genes were screened for altered submergence tolerance....... • The analysis identified 34 genes that were ubiquitously co-regulated by submergence and O2 deprivation. The biological functions of these include signaling, transcription, and anaerobic energy metabolism. HUPs comprised 40% of the co-regulated transcripts and mutants of seven of these genes were significantly...

Submerged Grove in Lake Onogawa

OpenAIRE

Sato, Yasuhiro; Nakamura, Soken; Ochiai, Masahiro

1996-01-01

Abstract : The first record by ultrasonic echo sounding on the distribution of the submerged standing trees on the bottom of Lake Onogawa is presented. Lake Onogawa is a dammed lake formed at the time of the eruption of the volcano Mt.Bandai in 1888. Since then the original vegetation of the dammed valley has remained submerged. Many submerged standing trees are distributed on the bottom within about 600m from the northeast end of the lake. The density of the trees in this area is sufficient ...

Eficácia do diquat no controle de Hydrilla verticillata, Egeria densa e Egeria najas e toxicidade aguda para o Guaru (Phallocerus caudimaculatus, em condições de laboratório Efficacy of diquat in the control of Hydrylla verticillata, Egeria densa and Egeria najas and its acute toxicity to Phallocerus caudimaculatus, under laboratory conditions

Directory of Open Access Journals (Sweden)

M.N.P. Henares

2011-06-01

Full Text Available No Brasil, as macrófitas aquáticas submersas, Egeria densa e Egeria najas, têm causado prejuízos aos usos múltiplos da água. Hydrilla verticillata foi recentemente introduzida, mas tem histórico como planta problemática nos EUA, no México e na Austrália. O objetivo deste trabalho foi avaliar as suscetibilidades relativas dessas três macrófitas aquáticas ao diquat e os riscos da utilização desse herbicida para o guaru (Phallocerus caudimaculatus. Para isso, foram instalados ensaios em condições de laboratório, a fim de avaliar a suscetibilidade relativa das três macrófitas por meio da manutenção de ponteiros dessas plantas em soluções contendo 0,0; 0,2; 0,4; 0,8; e 1,6 mg L-1 de diquat (Reward® por 14 dias. A avaliação foi realizada pela variação do acúmulo de matéria fresca e do comprimento dos ponteiros no período de exposição ao herbicida. H. verticillata mostrou maior sensibilidade ao diquat em comparação com as duas macrófitas do gênero Egeria, mesmo em baixas concentrações do herbicida. Nas maiores concentrações, E. densa mostrou maior sensibilidade que E. najas. O risco da aplicação do diquat para P. caudimaculatus foi estimado pela toxicidade aguda. Alevinos de P. caudimaculatus de 0,4 ± 0,2 mg foram expostos a soluções de 0,0; 1,0; 5,0; 10,0; 15,0; 20,0; 25,0; e 30,0 mg L-1 de diquat. A concentração letal de 50% (CL(I (50;96h do diquat estimada para P. caudimaculatus foi de 7,17 mg L-1. Para P. caudimaculatus, a toxicidade aguda foi superior à concentração recomendada para o controle de macrófitas aquáticas submersas, indicando risco muito baixo para esse peixe.In Brazil, the submerged plants Egeria densa and Egeria najas have caused damage to multiple uses of water. Hydrilla verticillata has been recently introduced, but it has a history as a problem plant in the U.S., Mexico and Australia. The objectives of this work were to assess the relative susceptibilities of these three

Microdistribution of {sup 241}Am in structures of submerged macrophyte Elodea canadensis growing in the Yenisei River

Energy Technology Data Exchange (ETDEWEB)

Bondareva, L., E-mail: lydiabondareva@gmail.co [Institute of Biophysics, Siberian Branch of Russian Academy of Sciences, 50 Akademgorodok, Krasnoyarsk 660036 (Russian Federation); Vlasova, I. [Chemistry Department Lomonosov Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Mogilnaya, O.; Bolsunovsky, A. [Institute of Biophysics, Siberian Branch of Russian Academy of Sciences, 50 Akademgorodok, Krasnoyarsk 660036 (Russian Federation); Kalmykov, S. [Chemistry Department Lomonosov Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation)

2010-01-15

A submerged macrophyte of the Yenisei River, Elodea canadensis, was used to study the microdistribution of the artificial radionuclide {sup 241}Am among different components of the plant. The total amount of {sup 241}Am added to the experimental system was 1850 +- 31 Bq/L. The total amount of {sup 241}Am accumulated by the plants was 182 Bq per sample, or 758,333 +- 385 Bq/kg dry mass. It has been found that the major portion of {sup 241}Am accumulated by E. canadensis, up to 85%, was bound to solid components of the cells. It is observed that the microdistribution of {sup 241}Am within different components of the submerged plant E. canadensis was not uniform. {sup 241}Am distribution vary depending on the age of the leaf blades, the state of the cells and morphological features of the plant stem.

Surviving floods: leaf gas films improve O₂ and CO₂ exchange, root aeration, and growth of completely submerged rice.

Science.gov (United States)

Pedersen, Ole; Rich, Sarah Meghan; Colmer, Timothy David

2009-04-01

When completely submerged, the leaves of some species retain a surface gas film. Leaf gas films on submerged plants have recently been termed 'plant plastrons', analogous with the plastrons of aquatic insects. In aquatic insects, surface gas layers (i.e. plastrons) enlarge the gas-water interface to promote O₂ uptake when under water; however, the function of leaf gas films has rarely been considered. The present study demonstrates that gas films on leaves of completely submerged rice facilitate entry of O₂ from floodwaters when in darkness and CO₂ entry when in light. O₂ microprofiles showed that the improved gas exchange was not caused by differences in diffusive boundary layers adjacent to submerged leaves with or without gas films; instead, reduced resistance to gas exchange was probably due to the enlarged water-gas interface (cf. aquatic insects). When gas films were removed artificially, underwater net photosynthesis declined to only 20% of the rate with gas films present, such that, after 7 days of complete submergence, tissue sugar levels declined, and both shoot and root growth were reduced. Internal aeration of roots in anoxic medium, when shoots were in aerobic floodwater in darkness or when in light, was improved considerably when leaf gas films were present. Thus, leaf gas films contribute to the submergence tolerance of rice, in addition to those traits already recognized, such as the shoot-elongation response, aerenchyma and metabolic adjustments to O₂ deficiency and oxidative stress. © 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Ltd.

Field studies of submerged-diffuser thermal plumes with comparisons to predictive model results

International Nuclear Information System (INIS)

Frigo, A.A.; Paddock, R.A.; Ditmars, J.D.

1976-01-01

Thermal plumes from submerged discharges of cooling water from two power plants on Lake Michigan were studied. The system for the acquisition of water temperatures and ambient conditions permitted the three-dimensional structure of the plumes to be determined. The Zion Nuclear Power Station has two submerged discharge structures separated by only 94 m. Under conditions of flow from both structures, interaction between the two plumes resulted in larger thermal fields than would be predicted by the superposition of single non-interacting plumes. Maximum temperatures in the near-field region of the plume compared favorably with mathematical model predictions. A comparison of physical-model predictions for the plume at the D. C. Cook Nuclear Plant with prototype measurements indicated good agreement in the near-field region, but differences in the far-field occurred as similitude was not preserved there

Optimization of submerged vane parameters

Indian Academy of Sciences (India)

H Sharma

the height or length of the submerged vane, no effective change in bed profile .... easily and again vanes will be ineffective, which is what. Odgaard and .... [3] Odgaard A J and Wang Y 1991a Sediment management with submerged vanes.

Oxidative stress mediated toxicity of TiO2 nanoparticles after a concentration and time dependent exposure of the aquatic macrophyte Hydrilla verticillata.

Science.gov (United States)

Spengler, Annette; Wanninger, Lena; Pflugmacher, Stephan

2017-09-01

The present study focused on oxidative stress effects in the aquatic macrophyte Hydrilla verticillata after exposure to titanium dioxide nanoparticles (TiO 2 -NPs). Experiments were conducted with different TiO 2 -NPs and concentrations (0.1 mg/L and 10 mg/L) in a time-dependent manner (0 h, 24 h, 48 h, 96 h, 168 h). To assess various levels of the oxidative stress response in H. verticillata, the level of hydrogen peroxide (H 2 O 2 ), the ratio of reduced to oxidized glutathione (GSH/GSSG), and activities of the antioxidative enzymes catalase (CAT) and glutathione reductase (GR) were evaluated. Study results imply oxidative stress effects after TiO 2 -NP exposure as adaptations in plant metabolism became apparent to counteract increased ROS formation. All TiO 2 -NPs caused elevated activities of the enzymes CAT and GR. Moreover, decreased ratios of GSH/GSSG indicated an activation of GSH-dependent pathways counteracting ROS formation. Plants exposed to a bulk-sized control revealed a size-dependent influence on the antioxidative stress response. As H 2 O 2 level increases were solely detected after exposure to 10 mg/L TiO 2 -NPs and nano-exposed plants showed normalization in its antioxidative stress response after 168h of exposure, it can be suggested that macrophytes are able to cope with currently predicted low-level exposures to TiO 2 -NPs. Copyright © 2017 Elsevier B.V. All rights reserved.

Data from: Identification of the submergence tolerance QTL come quick drowning1 (CQD1) in Arabidopsis thaliana

NARCIS (Netherlands)

Akman, Melis; Kleine, Rogier; Tienderen, van Peter H.; Schranz, M.E.

2017-01-01

Global climate change is predicted to increase water precipitation fluctuations and lead to localized prolonged floods in agricultural fields and natural plant communities. Thus, understanding the genetic basis of submergence tolerance is crucial in order to improve plant survival under these

Acoustic and adsorption properties of submerged wood

Science.gov (United States)

Hilde, Calvin Patrick

Wood is a common material for the manufacture of many products. Submerged wood, in particular, is used in niche markets, such as the creation of musical instruments. An initial study performed on submerged wood from Ootsa Lake, British Columbia, provided results that showed that the wood was not suitable for musical instruments. This thesis re-examined the submerged wood samples. After allowing the wood to age unabated in a laboratory setting, the wood was retested under the hypothesis that the physical acoustic characteristics would improve. It was shown, however, that the acoustic properties became less adequate after being left to sit. The adsorption properties of the submerged wood were examined to show that the submerged wood had a larger accessible area of wood than that of control wood samples. This implied a lower amount of crystalline area within the submerged wood. From the combined adsorption and acoustic data for the submerged wood, relationships between the moisture content and speed of sound were created and combined with previous research to create a proposed model to describe how the speed of sound varies with temperature, moisture content and the moisture content corresponding to complete hydration of sorption sites within the wood.

Species specificity of resistance to oxygen diffusion in thin cuticular membranes from amphibious plants

DEFF Research Database (Denmark)

Frost-Christensen, Henning; Jørgensen, Lise Bolt; Floto, Franz

2003-01-01

oxygen, diffusion, cuticula, amphibious plants, Hygrophila, Berula, Lobelia, Mentha, Potamogeton, Veronica, aquatic plants, submerged plants......oxygen, diffusion, cuticula, amphibious plants, Hygrophila, Berula, Lobelia, Mentha, Potamogeton, Veronica, aquatic plants, submerged plants...

Fluid-structure interaction of submerged structures

International Nuclear Information System (INIS)

Tang, H.T.; Becker, E.B.; Taylor, L.M.

1979-01-01

The purpose of the paper is to investigate fluid-structure interaction (FSI) of submerged structures in a confined fluid-structure system. Our particular interest is the load experienced by a rigid submerged structure subject to a pressure excitation in a fluid domain bounded by a structure which is either flexible or rigid. The objective is to see whether the load experienced by the submerged structure will be influenced by its confinement conditions. This investigation is intended to provide insight into the characteristics of FSI and answer the question as to whether one can obtain FSI independent data by constructing a small scale rigid submerged structure inside a flexible fluid-structure system. (orig.)

Development of a submerged gravel scrubber for containment venting applications: summary

International Nuclear Information System (INIS)

Hilliard, R.K.; McCormack, J.D.; Postma, A.K.

1981-01-01

Although hypothetical core disruptive accidents (HCDAs) are not design basis accidents for breeder reactor plants, extensive assessments of HCDA consequences have been made and design features for providing margins beyond the design base have been considered for future fast reactor plants. One feature proposed for increasing the safety margin is a containment vent and/or purge system which would mitigate the challenge to containment integrity resulting from excessive temperature and pressure or excessive hydrogen. A cleanup system would be required for removal of vented aerosols and condensible vapors to mitigate radiological consequences to the environment. A study is in progress at HEDL to select and develop a suitable air cleaning system for use in potential breeder reactor containment venting applications. A concept was conceived whereby the passiveness and high loading capacity of a water pool scrubber was combined with the high efficiency of a sand and gravel bed. It was termed a Submerged Gravel Scrubber (SGS). A schematic drawing of the concept is shown. The SGS consists of a bed of gravel (or other packing) submerged in a pool of water

Impeller Submergence Depth for Stirred Tanks

Directory of Open Access Journals (Sweden)

Thiyam T. Devi

2011-11-01

Full Text Available Impeller submergence governs the performance of mixing tanks employed in oxygen transfer operation. Present work experimentally investigates the effect of impeller submergence depths on oxygen transfer and corresponding power consumption. It has been found that at higher range of impeller submergence, mixing tanks consume less power and gives higher values of oxygen transfer coefficient. Optimal range of submergence depth is 0.7 to 0.9 times the impeller diameter. Copyright ©2011 BCREC UNDIP. All rights reserved.(Received: 4th March 2011; Revised: 12nd July 2011; Accepted: 14th July 2011[How to Cite: T.T. Devi, A.P. Sinha, M. Thakre, and B. Kumar. (2011. Impeller Submergence Depth for Stirred Tanks. Bulletin of Chemical Reaction Engineering & Catalysis, 6 (2: 123-128. doi:10.9767/bcrec.6.2.826.123-128][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.2.826.123-128 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/826] | View in 

Growth Control of Cyanobacteria by Three Submerged Macrophytes

Science.gov (United States)

Wang, Haiou; Zhong, Guangrong; Yan, Hai; Liu, Hu; Wang, Yao; Zhang, Chun

2012-01-01

Abstract To illustrate the control of harmful cyanobacterial growth and the removal of nutritients from fresh water, three submerged macrophytes were grown in the raw water of Guishui Lake. Lindernia rotundifolia, Hygrophila stricta, and Cryptocoryne crispatula were grown together in situ to assess their effectiveness in nutrient removal in microcosms. Results revealed the inhibitory effects of these species on cyanobacterial growth. In addition, water quality in the planted microcosms showed improvement when compared to the water quality of the unplanted microcosm. At all treatments studied, the chemical oxygen demand in the planted microcosms was lower than that in the unplanted microcosms, and the removal rate of all the nitrogen and phosphate in the planted microcosms was better than that of the microcosm without plants. Our study offers a useful algal control method for the lakes or reservoirs that suffer from harmful cyanobacterial blooms. PMID:22693412

IODINE REMOVAL EFFICIENCY IN NON-SUBMERGED AND SUBMERGED SELF-PRIMING VENTURI SCRUBBER

OpenAIRE

MAJID ALI; YAN CHANGQI; SUN ZHONGNING; GU HAIFENG; WANG JUNLONG; KHURRAM MEHBOOB

2013-01-01

The objective of this conducted research is to study the iodine removal efficiency in a self-priming venturi scrubber for submerged and non-submerged operating conditions experimentally and theoretically. The alkaline solution is used as an absorbent, which is prepared by dissolving sodium hydroxide (NaOH) and sodium thiosulphate (Na2S2O3) in water to remove the gaseous iodine (I2) from the gas. Iodine removal efficiency is examined at various gas flow rates and inlet concentrations of iodine...

Adaptações de plantas submersas à absorção do carbono inorgânico Adaptations of submerged plants to inorganic carbon uptake

Directory of Open Access Journals (Sweden)

Sandra Andréa Pierini

2004-09-01

Full Text Available No presente trabalho são discutidos alguns aspectos teóricos dos mecanismos e adaptações empregados pela vegetação submersa para maximizar o aproveitamento do carbono inorgânico na água. O tipo de estratégia utilizada pelas macrófitas aquáticas submersas deve-se a diferenças genéticas entre as espécies e também às condições ambientais predominantes. Vários mecanismos fisiológicos e morfológicos, como a utilização do metabolismo C4, do ácido das crassuláceas (CAM, a utilização do bicarbonato (HCO3-, a utilização do CO2 da água intersticial do sedimento e o desenvolvimento de folhas aéreas foram considerados as principais adaptações para evitar a limitação do carbono no ambiente aquático. De relevância ecológica, a utilização destas diferentes estratégias pode compensar baixas ofertas de CO2 às taxas fotossintéticas de várias espécies submersas e suprimir a fotorrespiração por garantir altas concentrações intracelulares de CO2. Assim, estes mecanismos são responsáveis, em parte, pelo sucesso das macrófitas aquáticas submersas em ambientes oligotróficos, com baixas concentrações de CO2.In this paper, the main theoretical aspects of the mechanisms and adaptations used by submerged vegetation to maximize the utilization of inorganic carbon are discussed. The type of strategy used by submerged plants is related to both genetic differences among species and environmental conditions. The use of C4 metabolism and crassulacean acid metabolism (CAM, uptake of bicarbonate (HCO3-, uptake of CO2 from interstitial (sediment water and the development of aerial leaves are considered the main physiological and morphological adaptations to avoid CO2 limitation. These mechanisms are ecologically important given that their utilization overcome the low CO2 availability to several submerged species. In addition, they suppress the photorespiration by increasing the intracellular CO2 concentrations. Thus, these

Submerged membrane distillation for desalination of water

KAUST Repository

Francis, Lijo; Ghaffour, NorEddine; Alsaadi, Ahmad Salem

2016-01-01

Submerged membrane modules for use for desalination of water are disclosed. In one or more aspects, the membrane modules can be submerged either in a feed solution tank or the feed solution can pass through the lumen side of the membrane submerged within the tank. The feed solution can be a water-based feed stream containing an amount of salt.

Submerged membrane distillation for desalination of water

KAUST Repository

Francis, Lijo

2016-10-27

Submerged membrane modules for use for desalination of water are disclosed. In one or more aspects, the membrane modules can be submerged either in a feed solution tank or the feed solution can pass through the lumen side of the membrane submerged within the tank. The feed solution can be a water-based feed stream containing an amount of salt.

Temperature-dependent development, cold tolerance, and potential distribution of Cricotopus lebetis (Diptera: Chironomidae), a tip miner of Hydrilla verticillata (Hydrocharitaceae).

Science.gov (United States)

Stratman, Karen N; Overholt, William A; Cuda, James P; Mukherjee, A; Diaz, R; Netherland, Michael D; Wilson, Patrick C

2014-10-15

A chironomid midge, Cricotopus lebetis (Sublette) (Diptera: Chironomidae), was discovered attacking the apical meristems of Hydrilla verticillata (L.f. Royle) in Crystal River, Citrus Co., Florida in 1992. The larvae mine the stems of H. verticillata and cause basal branching and stunting of the plant. Temperature-dependent development, cold tolerance, and the potential distribution of the midge were investigated. The results of the temperature-dependent development study showed that optimal temperatures for larval development were between 20 and 30°C, and these data were used to construct a map of the potential number of generations per year of C. lebetis in Florida. Data from the cold tolerance study, in conjunction with historical weather data, were used to generate a predicted distribution of C. lebetis in the United States. A distribution was also predicted using an ecological niche modeling approach by characterizing the climate at locations where C. lebetis is known to occur and then finding other locations with similar climate. The distributions predicted using the two modeling approaches were not significantly different and suggested that much of the southeastern United States was climatically suitable for C. lebetis. © The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.

PERFORMANCE OF NEWLY CONFIGURED SUBMERGED MEMBRANE BIOREACTOR FOR AEROBIC INDUSTRIAL WASTEWATER TREATMENT

Directory of Open Access Journals (Sweden)

I Gede Wenten

2012-02-01

Full Text Available The application of membrane to replace secondary clarifier of conventional activated sludge, known as membrane bioreactor, has led to a small footprint size of treatment with excellent effluent quality. The use of MBR eliminates almost all disadvantages encountered in conventional wastewater treatment plant such as low biomass concentration and washout of fine suspended solids. However, fouling remains as a main drawback. To minimize membrane fouling, a new configuration of submerged membrane bioreactor for aerobic industrial wastewater treatment has been developed. For the new configuration, a bed of porous particle is applied to cover the submerged ends-free mounted ultrafiltration membrane. Membrane performance was assessed based on flux productivity and selectivity. By using tapioca wastewater containing high organic matter as feed solution, reasonably high and stable fluxes around 11 l/m2.h were achieved with COD removal efficiency of more than 99%. The fouling analysis also shows that the newly configured ends-free membrane bioreactor exhibits lower irreversible resistance compared with the submerged one. In addition, the performance of pilot scale system, using a membrane module  with 10 m2 effective area and reactor tank with 120 L volume, was also assessed. The flux achieved from the pilot scale system around 8 l/m2.h with COD removal of more than 99%. Hence, this study has demonstrated the feasibility of the newly configured submerged ends-free MBR at larger scale.

MEMPELAJARI FISIOLOGI PENCEMARAN LINGKUNGAN DENGAN TEHNIK RADIOISOTOP (Study in the Physiology of Environment Pollution Using Radiotracer Method

Directory of Open Access Journals (Sweden)

Razak Achmad Hamzah

2011-11-01

Full Text Available ABSTRAK Penelitian ini bertujuan untuk mengetahui: 1. Perbedaan kemampuan daya serap tumbuhan air Hydrilla verticillata, Enceng gondok (Eichhomia crassipes dan Kangkung terhadap residu Malathion, menggunakan akuarium (diisi dengan air + Hydrilla Verticillata + Enceng Gondok + Kangkung + Malathion radioisotope 14C. 2. Perbandingan kadar malathion dalam jaringan ikan yang mendapat makanan Hydrilla verticilata dengan yang mendapat makanan kangkung, menggunakan: (akuarium pertama diisi air + Hydrilla Vericillata + ikan mas + Malathion radioisotope 14C; akuarium ke dua diisi air + kangkung + ikan mas + malathion radiisotop 14C. 3. Perbandingan ukuran penyerapan pada jaringan mammalia (tikus yang diberi makan jaringan ikan mas dengan yang diberi makan tumbuhan air (kangkung yang terkontaminasi. Jaringan ikan mas dan kangkung dilakukan pengabuan basah, lalu diberikan masing-masing kepada 30 ekor tikus. Kadar Malathion dari semua percobaan satu, dua dan tiga, diketahui dengan menggunakan alat pencacah Sintilator cair (Liquid Scintillation Spectrometer, LSC- 753 (ALOKA”. Hasil yang didapat dibandingkan dengan menggunakan uji-t Student. Hasil penelitian memperlihatkan bahwa: 1. Hydrilla Verticillata lebih efisien dari pada Enceng Gondok dan Kangkung dalam menyerap residu insektisida malathion dalam air. 2. Ikan yang diberi makan Hydrilla verticillata mengkonsentrasikan malathion lebih tinggi dari pada ikan yang diberi makan kangkung. 3. Mammalia (tikus yang mengkonsumsi daging ikan yang terkontaminasi akan mengkonsentrasikan malathion dalam tubuhnya lebih banyak dari pada tikus yang memakan sayuran (kangkung yang terkontaminasi. ABSTRACT The aim of this study is to determine: 1.The comparison of absorption by aquatic plants Hydrilla verticillata, water hyacinth and water spinach of Malathion insecticide residues in water, (aquarium filled with water + Hydrilla verticillata + water hyacinth + water spinach + 20 mci 14C malathion radioisotope; 2

Internal nitrogen removal from sediments by the hybrid system of microbial fuel cells and submerged aquatic plants.

Directory of Open Access Journals (Sweden)

Peng Xu

Full Text Available Sediment internal nitrogen release is a significant pollution source in the overlying water of aquatic ecosystems. This study aims to remove internal nitrogen in sediment-water microcosms by coupling sediment microbial fuel cells (SMFCs with submerged aquatic plants. Twelve tanks including four treatments in triplicates were designed: open-circuit (SMFC-o, closed-circuit (SMFC-c, aquatic plants with open-circuit (P-SMFC-o and aquatic plants with closed-circuit (P-SMFC-c. The changes in the bio-electrochemical characteristics of the nitrogen levels in overlying water, pore water, sediments, and aquatic plants were documented to explain the migration and transformation pathways of internal nitrogen. The results showed that both electrogenesis and aquatic plants could facilitate the mineralization of organic nitrogen in sediments. In SMFC, electrogenesis promoted the release of ammonium from the pore water, followed by the accumulation of ammonium and nitrate in the overlying water. The increased redox potential of sediments due to electrogenesis also contributed to higher levels of nitrate in overlying water when nitrification in pore water was facilitated and denitrification at the sediment-water interface was inhibited. When the aquatic plants were introduced into the closed-circuit SMFC, the internal ammonium assimilation by aquatic plants was advanced by electrogenesis; nitrification in pore water and denitrification in sediments were also promoted. These processes might result in the maximum decrease of internal nitrogen with low nitrogen levels in the overlying water despite the lower power production. The P-SMFC-c reduced 8.1%, 16.2%, 24.7%, and 25.3% of internal total nitrogen compared to SMFC-o on the 55th, 82th, 136th, and 190th days, respectively. The smaller number of Nitrospira and the larger number of Bacillus and Pseudomonas on the anodes via high throughput sequencing may account for strong mineralization and denitrification in the

Elevation dynamics in a restored versus a submerging salt marsh in Long Island Sound

Science.gov (United States)

Anisfeld, Shimon C.; Hill, Troy D.; Cahoon, Donald R.

2016-01-01

Accelerated sea-level rise (SLR) poses the threat of salt marsh submergence, especially in marshes that are relatively low-lying. At the same time, restoration efforts are producing new low-lying marshes, many of which are thriving and avoiding submergence. To understand the causes of these different fates, we studied two Long Island Sound marshes: one that is experiencing submergence and mudflat expansion, and one that is undergoing successful restoration. We examined sedimentation using a variety of methods, each of which captures different time periods and different aspects of marsh elevation change: surface-elevation tables, marker horizons, sediment cores, and sediment traps. We also studied marsh hydrology, productivity, respiration, nutrient content, and suspended sediment. We found that, despite the expansion of mudflat in the submerging marsh, the areas that remain vegetated have been gaining elevation at roughly the rate of SLR over the last 10 years. However, this elevation gain was only possible thanks to an increase in belowground volume, which may be a temporary response to waterlogging. In addition, accretion rates in the first half of the twentieth century were much lower than current rates, so century-scale accretion in the submerging marsh was lower than SLR. In contrast, at the restored marsh, accretion rates are now averaging about 10 mm yr−1 (several times the rate of SLR), much higher than before restoration. The main cause of the different trajectories at the two marshes appeared to be the availability of suspended sediment, which was much higher in the restored marsh. We considered and rejected alternative hypotheses, including differences in tidal flooding, plant productivity, and nutrient loading. In the submerging marsh, suspended and deposited sediment had relatively high organic content, which may be a useful indicator of sediment starvation.

Waste Treatment And Immobilization Plant U. S. Department Of Energy Office Of River Protection Submerged Bed Scrubber Condensate Disposition Project - Abstract # 13460

Energy Technology Data Exchange (ETDEWEB)

Yanochko, Ronald M [Washington River Protection Solutions, Richland, WA (United States); Corcoran, Connie [AEM Consulting, LLC, Richland, WA (United States)

2012-11-15

The Hanford Waste Treatment and Immobilization Plant (WTP) will generate an off-gas treatment system secondary liquid waste stream [submerged bed scrubber (SBS) condensate], which is currently planned for recycle back to the WTP Low Activity Waste (LAW) melter. This SBS condensate waste stream is high in Tc-99, which is not efficiently captured in the vitrified glass matrix. A pre-conceptual engineering study was prepared in fiscal year 2012 to evaluate alternate flow paths for melter off-gas secondary liquid waste generated by the WTP LAW facility. This study evaluated alternatives for direct off-site disposal of this SBS without pre-treatment, which mitigates potential issues associated with recycling.

Submerged cutting characteristics of abrasive suspension jet

International Nuclear Information System (INIS)

Shimizu, Seiji; Peng, Guoyi; Oguma, Yasuyuki; Nishikata, Hiroyuki

2015-01-01

An abrasive suspension jet (ASJ) formed by propelling abrasive suspension through a nozzle has a greater cutting capability than the conventional abrasive water jet. However the cutting capability of submerged ASJs decreases drastically with increasing the standoff distance and the pressure around the jet. A sheathed nozzle with ventilation for ASJs has been developed as a mean of extending the effective stand-off distance and improving the cutting capabilities under submerged condition. In the present investigation, cutting tests by ASJs in air and under submerged condition are conducted with specimens of aluminum alloy. Air coated ASJs are formed by using a sheathed nozzle with ventilation. The relative cutting depth is defined as the cutting depth under submerged condition divided by the cutting depth in air at the same standoff distance. The relative cutting depth is arranged effectually by the cavitation number based on the cavity pressure measured at the sheath. (author)

Multielement stoichiometry of submerged macrophytes across Yunnan plateau lakes (China).

Science.gov (United States)

Xing, Wei; Wu, Haoping; Shi, Qiao; Hao, Beibei; Liu, Han; Wang, Zhixiu; Liu, Guihua

2015-05-13

Stoichiometric homeostasis of element composition is one of the central concepts of ecological stoichiometry. We analyzed concentrations of macroelements (C, N, P, Ca, K, Mg, S), microelements (Cu, Fe, Mn, Mo, Ni, Zn) and beneficial elements (Na, Se, Si) in submerged macrophytes, water and sediments across 20 Yunnan plateau lakes. We predicted that tissue element composition in submerged macrophytes is affected by lake trophic level and taxonomy, and submerged macrophytes have weak stoichiometric homeostasis for all above 16 elements. Canonical discriminant analyses successfully discriminated among trophic level groups and taxa groups. Of all the elements, C, N, P and S most effectively discriminated among trophic level groups across 20 lakes, revealing lake trophic level mostly affect tissue macroelement composition in submerged macrophytes; while Ca, K and Se most effectively discriminated among submerged macrophytes taxa groups, suggesting taxonomy mostly affect compositions of macroelements and beneficial elements in submerged macrophytes. In addition, the stoichiometric homeostatic coefficient of 1/HCa:C for all five taxa of submerged macrophytes were less than zero, suggesting submerged macrophytes in Yunnan plateau lakes have strong Ca stoichiometric homeostasis. Our findings, not only broaden the knowledge of multielement stoichiometric homeostasis, but also help to choose most appropriate lake management strategy.

GID1 modulates stomatal response and submergence tolerance involving abscisic acid and gibberellic acid signaling in rice.

Science.gov (United States)

Du, Hao; Chang, Yu; Huang, Fei; Xiong, Lizhong

2015-11-01

Plant responses to abiotic stresses are coordinated by arrays of growth and developmental programs. Gibberellic acid (GA) and abscisic acid (ABA) play critical roles in the developmental programs and environmental responses, respectively, through complex signaling and metabolism networks. However, crosstalk between the two phytohormones in stress responses remains largely unknown. In this study, we report that GIBBERELLIN-INSENSITIVE DWARF 1 (GID1), a soluble receptor for GA, regulates stomatal development and patterning in rice (Oryza sativa L.). The gid1 mutant showed impaired biosynthesis of endogenous ABA under drought stress conditions, but it exhibited enhanced sensitivity to exogenous ABA. Scanning electron microscope and infrared thermal image analysis indicated an increase in the stomatal conductance in the gid1 mutant under drought conditions. Interestingly, the gid1 mutant had increased levels of chlorophyll and carbohydrates under submergence conditions, and showed enhanced reactive oxygen species (ROS)-scavenging ability and submergence tolerance compared with the wild-type. Further analyses suggested that the function of GID1 in submergence responses is partially dependent on ABA, and GA signaling by GID1 is involved in submergence tolerance by modulating carbohydrate consumption. Taken together, these findings suggest GID1 plays distinct roles in stomatal response and submergence tolerance through both the ABA and GA signaling pathways in rice. © 2014 Institute of Botany, Chinese Academy of Sciences.

Waste Treatment And Immobilization Plant U. S. Department Of Energy Office Of River Protection Submerged Bed Scrubber Condensate Disposition Project - Abstract no. 13460

International Nuclear Information System (INIS)

Yanochko, Ronald M; Corcoran, Connie

2012-01-01

The Hanford Waste Treatment and Immobilization Plant (WTP) will generate an off-gas treatment system secondary liquid waste stream [submerged bed scrubber (SBS) condensate], which is currently planned for recycle back to the WTP Low Activity Waste (LAW) melter. This SBS condensate waste stream is high in Tc-99, which is not efficiently captured in the vitrified glass matrix. A pre-conceptual engineering study was prepared in fiscal year 2012 to evaluate alternate flow paths for melter off-gas secondary liquid waste generated by the WTP LAW facility. This study evaluated alternatives for direct off-site disposal of this SBS without pre-treatment, which mitigates potential issues associated with recycling

Application of ADM1 for modeling of biogas production from anaerobic digestion of Hydrilla verticillata.

Science.gov (United States)

Chen, Xiaojuan; Chen, Zhihua; Wang, Xun; Huo, Chan; Hu, Zhiquan; Xiao, Bo; Hu, Mian

2016-07-01

The present study focused on the application of anaerobic digestion model no. 1 (ADM1) to simulate biogas production from Hydrilla verticillata. Model simulation was carried out by implementing ADM1 in AQUASIM 2.0 software. Sensitivity analysis was used to select the most sensitive parameters for estimation using the absolute-relative sensitivity function. Among all the kinetic parameters, disintegration constant (kdis), hydrolysis constant of protein (khyd_pr), Monod maximum specific substrate uptake rate (km_aa, km_ac, km_h2) and half-saturation constants (Ks_aa, Ks_ac) affect biogas production significantly, which were optimized by fitting of the model equations to the data obtained from batch experiments. The ADM1 model after parameter estimation was able to well predict the experimental results of daily biogas production and biogas composition. The simulation results of evolution of organic acids, bacteria concentrations and inhibition effects also helped to get insight into the reaction mechanisms. Copyright © 2016. Published by Elsevier Ltd.

A Survey of the Invasive Aquatic and Riparian Plants of the Low Rio Grande

Science.gov (United States)

2005-04-01

many areas. In 2001 and 2003, surveys were conducted starting below Amistad Reservoir to immediately below Falcon Reservoir to assess the...River were surveyed from Amistad Reservoir to Anzulduas Dam for the presence of hydrilla and other invasive aquatic weed species (Grodowitz et al...to difficulties in accessing the river. During the 2001 survey, hydrilla was found in Amistad Reservoir and below Falcon Reservoir. In August 2002

Effects of taxonomy, sediment, and water column on C:N:P stoichiometry of submerged macrophytes in Yangtze floodplain shallow lakes, China.

Science.gov (United States)

Su, Haojie; Wu, Yao; Xie, Ping; Chen, Jun; Cao, Te; Xia, Wulai

2016-11-01

Carbon (C), nitrogen (N) and phosphorus (P) are the three most important essential elements limiting growth of primary producers. Submerged macrophytes generally absorb nutrients from sediments by root uptake. However, the C:N:P stoichiometric signatures of plant tissue are affected by many additional factors such as taxonomy, nutrient availability, and light availability. We first revealed the relative importance of taxonomy, sediment, and water column on plant C:N:P stoichiometry using variance partitioning based on partial redundancy analyses. Results showed that taxonomy was the most important factor in determining C:N:P stoichiometry, then the water column and finally the sediment. In this study, a significant positive relationship was found between community C concentration and macrophyte community biomass, indicating that the local low C availability in macrophytes probably was the main reason why submerged macrophytes declined in Yangtze floodplain shallow lakes. Based on our study, it is suggested that submerged macrophytes in Yangtze floodplain shallow lakes are primarily limited by low light levels rather than nutrient availability.

Flow and scour around vertical submerged structures

Indian Academy of Sciences (India)

The safety of the foundations of submerged hydraulic structures due to excessive local scour is threatened by the erosive action of the waves and currents passing around these structures. Fish and aquatic habitat is seriously affected due to the modification of the flow field caused by these submerged structures. Hence, the ...

Aquatic Plant Control Research Program

National Research Council Canada - National Science Library

Cofrancesco, Alfred

1998-01-01

... (Mydophyllum spice turn) and hydrilla (Hyddlla verticfflata). These species, which account for more that two thirds of all noxious aquatic weed acreage in the United States, have similar characteristics...

Preliminary Analysis of a Submerged Wave Energy Device

Science.gov (United States)

Wagner, J. R.; Wagner, J. J.; Hayatdavoodi, M.; Ertekin, R. C.

2016-02-01

Preliminary analysis of a submerged wave energy harvesting device is presented. The device is composed of a thin, horizontally submerged plate that is restricted to heave oscillations under the influence of surface waves. The submerged plate is oscillating, and it can be attached to a fixed rotor, or a piston, to harvest the wave energy. A fully submerged wave energy converter is preferred over a surface energy convertor due to its durability and less visual and physical distractions it presents. In this study, the device is subject to nonlinear shallow-water waves. Wave loads on the submerged oscillating plate are obtained via the Level I Green-Naghdi equations. The unsteady motion of the plate is obtained by solving the nonlinear equations of motion. The results are obtained for a range of waves with varying heights and periods. The amplitude and period of plate oscillations are analyzed as functions of the wave parameters and plate width. Particular attention is given to the selection of the site of desired wave field. Initial estimation on the amount of energy extraction from the device, located near shore at a given site, is provided.

ALTERNATE FOOD-CHAIN TRANSFER OF THE TOXIN LINKED TO AVIAN VACUOLAR MYELINOPATHY AND IMPLICATIONS FOR THE ENDANGERED FLORIDA SNAIL KITE (ROSTRHAMUS SOCIABILIS).

Science.gov (United States)

Dodd, Shelley R; Haynie, Rebecca S; Williams, Susan M; Wilde, Susan B

2016-04-28

Avian vacuolar myelinopathy (AVM) is a neurologic disease causing recurrent mortality of Bald Eagles ( Haliaeetus leucocephalus ) and American Coots ( Fulica americana ) at reservoirs and small impoundments in the southern US. Since 1994, AVM is considered the cause of death for over 170 Bald Eagles and thousands of American Coots and other species of wild birds. Previous studies link the disease to an uncharacterized toxin produced by a recently described cyanobacterium, Aetokthonos hydrillicola gen. et sp. nov. that grows epiphytically on submerged aquatic vegetation (SAV). The toxin accumulates, likely in the gastrointestinal tract of waterbirds that consume SAV, and birds of prey are exposed when feeding on the moribund waterbirds. Aetokthonos hydrillicola has been identified in all reservoirs where AVM deaths have occurred and was identified growing abundantly on an exotic SAV hydrilla ( Hydrilla verticillata ) in Lake Tohopekaliga (Toho) in central Florida. Toho supports a breeding population of a federally endangered raptor, the Florida Snail Kite ( Rostrhamus sociabilis ) and a dense infestation of an exotic herbivorous aquatic snail, the island applesnail ( Pomacea maculata ), a primary source of food for resident Snail Kites. We investigated the potential for transmission in a new food chain and, in laboratory feeding trials, confirmed that the AVM toxin was present in the hydrilla/A. hydrillicola matrix collected from Toho. Additionally, laboratory birds that were fed apple snails feeding on hydrilla/A. hydrillicola material from a confirmed AVM site displayed clinical signs (3/5), and all five developed brain lesions unique to AVM. This documentation of AVM toxin in central Florida and the demonstration of AVM toxin transfer through invertebrates indicate a significant risk to the already diminished population of endangered Snail Kites.

Design of extended length submerged traveling screen and submerged bar screen fish guidance equipment

International Nuclear Information System (INIS)

Bardy, D.; Lindstrom, M.; Fechner, D.

1991-01-01

The hydropower projects on the Snake and lower Columbia Rivers in the Pacific Northwest are unique because these rivers are also the spawning grounds for migratory salmon. The salmon swim upstream from the ocean, lay their eggs, and die. The newly hatched fingerlings must then make their way past the hydroelectric dams to the ocean. Two separate bypass systems are needed, one to pass the adult fish going upstream, and one to pass the fingerlings going downstream. This paper addresses the design considerations for two of the components of the downstream migrant fish passage facilities, the extended Submerged Traveling Screen and Submerged Bar Screen

[Algal control ability of allelopathically active submerged macrophytes: a review].

Science.gov (United States)

Xiao, Xi; Lou, Li-ping; Li, Hua; Chen, Ying-xu

2009-03-01

The inhibitory effect of allelochemicals released by submerged macrophytes on phytoplankton is considered as one of the mechanisms that contribute to the stabilization of clear-water status in shallow lakes. This paper reviewed the research progress in the allelopathy of submerged macrophytes on algae from the aspects of the occurrence frequency and coverage of allelopathically active submerged macrophytes in lakes, and the kinds and allelopathical effects of the allelochemicals released from the macrophytes. The previous researches indicated that allelopathically active submerged macrophyte species such as Myriophyllum, Ceratophyllum, and Elodea were efficient to control phytoplankton, especially when their biomass was high enough, and the dominant algae were sensitive species. The allelochemicals such as hydroxybenzene released by the submerged macrophytes could inhibit the growth of algae. Different phytoplankton species exhibited different sensitivity against allelochemicals, e.g., cyanobacteria and diatom were more sensitive than green algae, while epiphytic species were less sensitive than phytoplankton. Environmental factors such as light, temperature, and nutrients could significantly affect the allelopathical effect of submerged macrophytes. The research of the allelopathy of submerged macrophytes is still at its beginning, and further researches are needed on the effects of environmental factors on the allelopathy, extraction and identification of allelochemicals, selective algal control mechanisms, and metabolism of the allelochmicals.

Benefits of flooding-induced aquatic adventitious roots depend on the duration of submergence: linking plant performance to root functioning.

Science.gov (United States)

Zhang, Qian; Huber, Heidrun; Beljaars, Simone J M; Birnbaum, Diana; de Best, Sander; de Kroon, Hans; Visser, Eric J W

2017-07-01

Temporal flooding is a common environmental stress for terrestrial plants. Aquatic adventitious roots (aquatic roots) are commonly formed in flooding-tolerant plant species and are generally assumed to be beneficial for plant growth by supporting water and nutrient uptake during partial flooding. However, the actual contribution of these roots to plant performance under flooding has hardly been quantified. As the investment into aquatic root development in terms of carbohydrates may be costly, these costs may - depending on the specific environmental conditions - offset the beneficial effects of aquatic roots. This study tested the hypothesis that the balance between potential costs and benefits depends on the duration of flooding, as the benefits are expected to outweigh the costs in long-term but not in short-term flooding. The contribution of aquatic roots to plant performance was tested in Solanum dulcamara during 1-4 weeks of partial submergence and by experimentally manipulating root production. Nutrient uptake by aquatic roots, transpiration and photosynthesis were measured in plants differing in aquatic root development to assess the specific function of these roots. As predicted, flooded plants benefited from the presence of aquatic roots. The results showed that this was probably due to the contribution of roots to resource uptake. However, these beneficial effects were only present in long-term but not in short-term flooding. This relationship could be explained by the correlation between nutrient uptake and the flooding duration-dependent size of the aquatic root system. The results indicate that aquatic root formation is likely to be selected for in habitats characterized by long-term flooding. This study also revealed only limited costs associated with adventitious root formation, which may explain the maintenance of the ability to produce aquatic roots in habitats characterized by very rare or short flooding events. © The Author 2017. Published by

Submerged Membrane Bioreactor (sMBR: a promising alternative to wastewater treatment for water reuse

Directory of Open Access Journals (Sweden)

Eduardo Lucas Subtil

2013-12-01

Full Text Available Treatment technology for wastewater treatment and reuse encompasses a vast number of options, and the Submerged Membrane Bioreactor is regarded as a key element for the role it can play in water reuse schemes. Thus, this study aimed to present and discuss the current status of sMBR implementation, as well as to present the results of a pilot plant with submerged flat sheet membranes treating wastewater from the residence halls and the restaurant of the University of São Paulo. The pilot plant was operated under stationary conditions over a period of 90 days with a concentration of 3422 ± 693 mg TSS/L. The results showed that the system can produce an effluent with low concentrations of color, turbidity, COD and BOD5 with values of 25 uC, 0.29 NTU, 5.5 mg O2/L and 24 mg O2/L, respectively. Furthermore, the ultrafiltration membranes used were able to reduce the density of pathogen indicators, with removal of 7 and 6 log of thermotolerant coliforms and E. coli respectively, resulting with concentrations of 9,3 ± 21,0 e 1,8 ± 4,0 MPN/100 mL, respectively.

Submerged cutting characteristics of abrasive suspension jet

International Nuclear Information System (INIS)

Shimizu, Seiji; Peng, Guoyi; Oguma, Yasuyuki; Nishikata, Hiroki

2015-01-01

An abrasive suspension jet (ASJ) formed by propelling abrasive suspension through a nozzle has a greater cutting capability than the conventional abrasive water jet. However the cutting capability of submerged ASJs decreases drastically with increasing the standoff distance and the pressure around the jet. A sheathed nozzle nozzle with ventilation for ASJs has been developed as a mean of extending the effective stand-off distance and improving the cutting capabilities under submerged condition. In the present investigation, cutting tests by ASJs in air and under submerged condition are conducted with specimens of aluminum alloy. Air coated ASJs are formed by using a sheathed nozzle with ventilation. The relative cutting depth is defined as the cutting depth is arranged effectually by the cavitation number based on the cavity pressure measured at the sheath. (author)

Allelic variants of OsSUB1A cause differential expression of transcription factor genes in response to submergence in rice.

Science.gov (United States)

Sharma, Niharika; Dang, Trang Minh; Singh, Namrata; Ruzicic, Slobodan; Mueller-Roeber, Bernd; Baumann, Ute; Heuer, Sigrid

2018-01-08

Flooding during seasonal monsoons affects millions of hectares of rice-cultivated areas across Asia. Submerged rice plants die within a week due to lack of oxygen, light and excessive elongation growth to escape the water. Submergence tolerance was first reported in an aus-type rice landrace, FR13A, and the ethylene-responsive transcription factor (TF) gene SUB1A-1 was identified as the major tolerance gene. Intolerant rice varieties generally lack the SUB1A gene but some intermediate tolerant varieties, such as IR64, carry the allelic variant SUB1A-2. Differential effects of the two alleles have so far not been addressed. As a first step, we have therefore quantified and compared the expression of nearly 2500 rice TF genes between IR64 and its derived tolerant near isogenic line IR64-Sub1, which carries the SUB1A-1 allele. Gene expression was studied in internodes, where the main difference in expression between the two alleles was previously shown. Nineteen and twenty-six TF genes were identified that responded to submergence in IR64 and IR64-Sub1, respectively. Only one gene was found to be submergence-responsive in both, suggesting different regulatory pathways under submergence in the two genotypes. These differentially expressed genes (DEGs) mainly included MYB, NAC, TIFY and Zn-finger TFs, and most genes were downregulated upon submergence. In IR64, but not in IR64-Sub1, SUB1B and SUB1C, which are also present in the Sub1 locus, were identified as submergence responsive. Four TFs were not submergence responsive but exhibited constitutive, genotype-specific differential expression. Most of the identified submergence responsive DEGs are associated with regulatory hormonal pathways, i.e. gibberellins (GA), abscisic acid (ABA), and jasmonic acid (JA), apart from ethylene. An in-silico promoter analysis of the two genotypes revealed the presence of allele-specific single nucleotide polymorphisms, giving rise to ABRE, DRE/CRT, CARE and Site II cis-elements, which

Submerged cultivation of medicinal mushrooms: bioprocesses and products (review).

Science.gov (United States)

Elisashvili, Vladimir

2012-01-01

Medicinal mushrooms belonging to higher Basidiomycetes are an immensely rich yet largely untapped resource of useful, easily accessible, natural compounds with various biological activities that may promote human well-being. The medicinal properties are found in various cellular components and secondary metabolites (polysaccharides, proteins and their complexes, phenolic compounds, polyketides, triterpenoids, steroids, alkaloids, nucleotides, etc.), which have been isolated and identified from the fruiting bodies, culture mycelium, and culture broth of mushrooms. Some of these compounds have cholesterol-lowering, anti-diabetic, antioxidant, antitumor, immunomodulating, antimicrobial, and antiviral activities ready for industrial trials and further commercialization, while others are in various stages of development. Recently, the submerged cultivation of medicinal mushrooms has received a great deal of attention as a promising and reproducible alternative for the efficient production of mushroom mycelium and metabolites. Submerged cultivation of mushrooms has significant industrial potential, but its success on a commercial scale depends on increasing product yields and development of novel production systems that address the problems associated with this technique of mushroom cultivation. In spite of many researchers' efforts for the production of bioactive metabolites by mushrooms, the physiological and engineering aspects of submerged cultures are still far from being thoroughly studied. The vast majority of studies have focused on polysaccharide and ganoderic acid production in submerged cultivation of medicinal mushrooms, and very little has been written so far on the antioxidant and hemagglutinating activity of submerged mushroom cultures. The purpose of this review is to provide an update of the present state of the art and future prospects of submerged cultivation of medicinal mushrooms to produce mycelium and bioactive metabolites, and to make a

[Effects of light on submerged macrophytes in eutrophic water: research progress].

Science.gov (United States)

Li-Sha, Zou; Ze-Yu, Nie; Xiao-Yan, Yao; Ji-Yan, Shi

2013-07-01

The restoration of submerged macrophytes is the key to remediate eutrophic water and maintain the health of aquatic ecosystem, while light is the main limiting factor. This paper summarized the factors affecting the light extinction in water and the mechanisms of light intensity affecting the physiology of submerged macrophytes, with the focuses on the metabolic mechanisms of carbon, nitrogen, and phosphorus, the responses of antioxidant enzyme system, and the feedbacks of pigment composition and concentration in the common submerged macrophytes under low light stress. Several engineering techniques applied in the ecological restoration of submerged macrophytes were presented, and the framework of the restoration of submerged macrophytes in eutrophic water was proposed. Some problems in current research and several suggestions on future research were addressed, which could help the related research and engineering practices.

Transcriptomic Analysis of Gibberellin- and Paclobutrazol-Treated Rice Seedlings under Submergence

Directory of Open Access Journals (Sweden)

Jing Xiang

2017-10-01

Full Text Available Submergence stress is a limiting factor for rice growing in rainfed lowland areas of the world. It is known that the phytohormone gibberellin (GA has negative effects on submergence tolerance in rice, while its inhibitor paclobutrazol (PB does the opposite. However, the physiological and molecular basis underlying the GA- and PB-regulated submergence response remains largely unknown. In this study, we reveal that PB could significantly enhance rice seedling survival by retaining a higher level of chlorophyll content and alcohol dehydrogenase activity, and decelerating the consumption of non-structure carbohydrate when compared with the control and GA-treated samples. Further transcriptomic analysis identified 3936 differentially expressed genes (DEGs among the GA- and PB-treated samples and control, which are extensively involved in the submergence and other abiotic stress responses, phytohormone biosynthesis and signaling, photosynthesis, and nutrient metabolism. The results suggested that PB enhances rice survival under submergence through maintaining the photosynthesis capacity and reducing nutrient metabolism. Taken together, the current study provided new insight into the mechanism of phytohormone-regulated submergence response in rice.

Submergence analysis of the proposed Ken Betwa Dam (Madhya Pradesh India, using geospatial technology in Environmental Impact Assessments

Directory of Open Access Journals (Sweden)

Goparaju Laxmi

2017-12-01

Full Text Available This study has analysed the Landsat 8 OLI data (December 2016 to delineate the various land use/land cover classes of the area which will be submerged by the proposed Daudhan/Greater Gangau Dam, which is part of the proposed Ken Betwa River Link Project (in the Madhya Pradesh state of India and also the area likely to be submerged in the Panna Tiger Reserve (PTR. The proposed area of submergence was computed at various full reservoir lengths (FRL, 278 m, 283 m, 288 m, 289 m and 293 m. Similarly the area of submergence for the Panna Tiger Reserve was computed at the mentioned FRLs. It was concluded that a large part of the Panna Tiger Reserve would be submerged and habitat of various animals and plants would be under threat. In comparison with the figures given in the Environmental Impact Assessment certain serious discrepancies and weaknesses were detected and it was felt that they should have been addressed. The results were compared with the EIA – EMP report of the Ken-Betwa link project, Phase 1, prepared by Agricultural Finance Corporation Limited for the National Water Development Agency (Ministry of Water Resources, River Development and Ganga Rejuvenation, Government of India. A proper evaluation of the negative impacts would help when making relevant decisions and appropriate steps to ensure that the loss is kept to a minimum. Safeguarding the biodiversity of forests and wildlife habitats should be the priority as their loss is irreplaceable. Geospatial technology helps in studying the overall spatial view of the proposed submergence area and the visualization gives a clear picture of the likely scenario in the future. It would assist in decision making and mitigation measures.

Proceedings, Annual Meeting, Aquatic Plant Control Research Program (17th) Held at Sacramento, California on 16-18 November 1982.

Science.gov (United States)

1983-06-01

inhibit the germination of lettuce seeds (Baltrop and Martin 1983). Several observations are pertinent: (1) the effect is concentration dependent; (2) the...formulations of dichlobenil and fluridone were evaluated for control of hydrilla regrowth from rootstocks and from germinating tubers. Hydrilla tubers were...Carriers for Controlled Release of Fluridone -R. L. Dunn, Southern Research Institute Birmingham, Alabama 10:55 a.m. Herbicide Evaluation Program -T. K. Van

Hurricane Effects on a Shallow Lake Ecosystem and Its Response to a Controlled Manipulation of Water Level

Directory of Open Access Journals (Sweden)

Karl E. Havens

2001-01-01

Full Text Available In order to reverse the damage to aquatic plant communities caused by multiple years of high water levels in Lake Okeechobee, Florida (U.S., the Governing Board of the South Florida Water Management District (SFWMD authorized a "managed recession" to substantially lower the surface elevation of the lake in spring 2000. The operation was intended to achieve lower water levels for at least 8 weeks during the summer growing season, and was predicted to result in a large-scale recovery of submerged vascular plants. We treated this operation as a whole ecosystem experiment, and assessed ecological responses using data from an existing network of water quality and submerged plant monitoring sites. As a result of large-scale discharges of water from the lake, coupled with losses to evaporation and to water supply deliveries to agriculture and other regional users, the lake surface elevation receded by approximately 1 m between April and June. Water depths in shoreline areas that historically supported submerged plant communities declined from near 1.5 m to below 0.5 m. Low water levels persisted for the entire summer. Despite shallow depths, the initial response (in June 2000 of submerged plants was very limited and water remained highly turbid (due at first to abiotic seston and later to phytoplankton blooms. Turbidity decreased in July and the biomass of plants increased. However, submerged plant biomass did not exceed levels observed during summer 1999 (when water depths were greater until August. Furthermore, a vascular plant-dominated assemblage (Vallisnera, Potamogeton, and Hydrilla that occurred in 1999 was replaced with a community of nearly 98% Chara spp. (a macro-alga in 2000. Hence, the lake’s submerged plant community appeared to revert to an earlier successional stage despite what appeared to be better conditions for growth. To explain this unexpected response, we evaluated the impacts that Hurricane Irene may have had on the lake in the

Hurricane effects on a shallow lake ecosystem and its response to a controlled manipulation of water level.

Science.gov (United States)

Havens, K E; Jin, K R; Rodusky, A J; Sharfstein, B; Brady, M A; East, T L; Iricanin, N; James, R T; Harwell, M C; Steinman, A D

2001-04-04

In order to reverse the damage to aquatic plant communities caused by multiple years of high water levels in Lake Okeechobee, Florida (U.S.), the Governing Board of the South Florida Water Management District (SFWMD) authorized a "managed recession" to substantially lower the surface elevation of the lake in spring 2000. The operation was intended to achieve lower water levels for at least 8 weeks during the summer growing season, and was predicted to result in a large-scale recovery of submerged vascular plants. We treated this operation as a whole ecosystem experiment, and assessed ecological responses using data from an existing network of water quality and submerged plant monitoring sites. As a result of large-scale discharges of water from the lake, coupled with losses to evaporation and to water supply deliveries to agriculture and other regional users, the lake surface elevation receded by approximately 1 m between April and June. Water depths in shoreline areas that historically supported submerged plant communities declined from near 1.5 m to below 0.5 m. Low water levels persisted for the entire summer. Despite shallow depths, the initial response (in June 2000) of submerged plants was very limited and water remained highly turbid (due at first to abiotic seston and later to phytoplankton blooms). Turbidity decreased in July and the biomass of plants increased. However, submerged plant biomass did not exceed levels observed during summer 1999 (when water depths were greater) until August. Furthermore, a vascular plant-dominated assemblage (Vallisneria, Potamogeton, and Hydrilla) that occurred in 1999 was replaced with a community of nearly 98% Chara spp. (a macro-alga) in 2000. Hence, the lake"s submerged plant community appeared to revert to an earlier successional stage despite what appeared to be better conditions for growth. To explain this unexpected response, we evaluated the impacts that Hurricane Irene may have had on the lake in the previous

On-line vibration monitoring for submerged vertical shaft pumps: Final report

International Nuclear Information System (INIS)

Walter, T.J.; Marchione, M.M.

1988-03-01

The overall goal of this project was to extend to vertical pumps the capability that presently exists to monitor and diagnose vibration problems in horizontal pumps. Specific objectives included the development of analytical techniques to interpret vibration measurements, the verification of these techniqeus by in-plant tests, and the development of recommendations for procuring submergible vibration sensors. A concurrent analytical and experimental approach was used to accomplish these objectives. Rotordynamic analyses of selected pumps were accomplished, and each pump was instrumented and monitored for extended periods of time. The models were used to determine important frequencies and optimum sensor locations and to predict the effect that wear, imbalance, misalighment, and other mechanical changes would have on measured vibration. The predictive ability of the models was confirmed by making changes to instrumented pumps and observing actual changes in pump vibration. Simplified guidelines have been developed to assist the interested user to develop a computer model that realistically predicts the rotordynamic performance of the installed pump. Based on the work accomplished, typical sensor locations have been established. Experience gained in application of commercially available submergible sensors is also related. 11 refs., 11 figs

Photosynthetic carbon metabolism in the submerged aquatic angiosperm Scirpus subterminalis

Energy Technology Data Exchange (ETDEWEB)

Beer, S; Wetzel, R G

1981-01-01

Scirpus subterminalis Torr., a submerged angiosperm abundant in many hardwater lakes of the Great Lakes region, was investigated for various photosynthetic carbon fixation properties in relation to available inorganic carbon and levels of carbon fixing enzymes. Photosynthetic experiments were CO/sub 2/ and HCO/sub 3//sup -/ were supplied at various concentrations showed that Scirpus was able to utilize HCO/sub 3//sup -/ at those concentrations close to natural conditions. However, when CO/sub 2/ concentrations were increased above ambient, photosynthetic rates increased markedly. It was concluded that the photosynthetic potential of this plant in many natural situations may be limited by inorganic carbon uptake in the light. Phosphoenolpyruvate carboxylase (PEPcase)/ribulose-1,5-bisphosphate carboxylase (ruBPcase) ratios of the leaves varied between 0.5 and 0.9 depending on substrate concentration during assay. The significance of PEP-mediated carbon fixation of Scirpus (basically a C/sub 3/ plant) in the dark was investigated. Malate accumulated in the leaves during the dark period of a 24-h cycle and malate levels decreased significantly during the following light period. The accumulation was not due to transport of malate from the roots. Carbon uptake rates in the dark by the leaves of Scirpus were lower than malate accumulation rates. Therefore, part of the malate was likely derived from respired CO/sub 2/. Carbon uptake rates in the light were much higher than malate turnover rates. It was estimated that carbon fixation via malate could contribute up to 12% to net photosynthetic rates. The ecological significance of this type of metabolism in submerged aquatics is discussed.

Contrasting Changes Caused by Drought and Submergence Stresses in Bermudagrass (Cynodon dactylon)

Science.gov (United States)

Ye, Tiantian; Shi, Haitao; Wang, Yanping; Chan, Zhulong

2015-01-01

In this study, we investigated the mechanisms by which bermudagrass withstands the drought and submergence stresses through physiological, proteomic and metabolomic approaches. The results showed that significant physiological changes were observed after drought treatment, while only slight changes after submergence treatment, including compatible solute contents, ROS levels and antioxidant enzyme activities. Proteomics results showed that 81 proteins regulated by drought or submergence treatment were identified by MALDI-TOF-MS. Among them, 76 proteins were modulated by drought stress with 46 increased abundance and 30 decreased abundance. Forty-five showed abundance changes after submergence treatment with 10 increased and 35 decreased. Pathway enrichment analysis revealed that pathways of amino acid metabolism and mitochondrial electron transport/ATP synthesis were only enriched by drought treatment, while other pathways including photosynthesis, biodegradation of xenobiotics, oxidative pentose phosphate, glycolysis and redox were commonly over-represented after both drought and submergence treatments. Metabolomic analysis indicated that most of the metabolites were up-regulated by drought stress, while 34 of 40 metabolites contents exhibited down-regulation or no significant changes when exposed to submergence stress, including sugars and sugar alcohols. These data indicated that drought stress extensively promoted photosynthesis and redox metabolisms while submergence stress caused declined metabolisms and dormancy in Cynodon dactylon. Taken together, the quiescence strategy with retarded growth might allow bermudagrass to be adaptive to long-term submerged environment, while activation of photosynthesis and redox, and accumulation of compatible solutes and molecular chaperones increased bermudagrass tolerance to drought stress. PMID:26617615

Submergible barge retrievable storage and permanent disposal system for radioactive waste

Science.gov (United States)

Goldsberry, Fred L.; Cawley, William E.

1981-01-01

A submergible barge and process for submerging and storing radioactive waste material along a seabed. A submergible barge receives individual packages of radwaste within segregated cells. The cells are formed integrally within the barge, preferably surrounded by reinforced concrete. The cells are individually sealed by a concrete decking and by concrete hatch covers. Seawater may be vented into the cells for cooling, through an integral vent arrangement. The vent ducts may be attached to pumps when the barge is bouyant. The ducts are also arranged to promote passive ventilation of the cells when the barge is submerged. Packages of the radwaste are loaded into individual cells within the barge. The cells are then sealed and the barge is towed to the designated disposal-storage site. There, the individual cells are flooded and the barge will begin descent controlled by a powered submarine control device to the seabed storage site. The submerged barge will rest on the seabed permanently or until recovered by a submarine control device.

The Performance and Fouling Control of Submerged Hollow Fiber (HF Systems: A Review

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Ebrahim Akhondi

2017-07-01

Full Text Available The submerged membrane filtration concept is well-established for low-pressure microfiltration (MF and ultrafiltration (UF applications in the water industry, and has become a mainstream technology for surface-water treatment, pretreatment prior to reverse osmosis (RO, and membrane bioreactors (MBRs. Compared to submerged flat sheet (FS membranes, submerged hollow fiber (HF membranes are more common due to their advantages of higher packing density, the ability to induce movement by mechanisms such as bubbling, and the feasibility of backwashing. In view of the importance of submerged HF processes, this review aims to provide a comprehensive landscape of the current state-of-the-art systems, to serve as a guide for further improvements in submerged HF membranes and their applications. The topics covered include recent developments in submerged hollow fiber membrane systems, the challenges and developments in fouling-control methods, and treatment protocols for membrane permeability recovery. The highlighted research opportunities include optimizing the various means to manipulate the hydrodynamics for fouling mitigation, developing online monitoring devices, and extending the submerged HF concept beyond filtration.

Strong Genetic Differentiation of Submerged Plant Populations across Mountain Ranges: Evidence from Potamogeton pectinatus in Iran.

Science.gov (United States)

Abbasi, Shabnam; Afsharzadeh, Saeed; Saeidi, Hojjatollah; Triest, Ludwig

2016-01-01

Biogeographic barriers for freshwater biota can be effective at various spatial scales. At the largest spatial scale, freshwater organisms can become genetically isolated by their high mountain ranges, vast deserts, and inability to cross oceans. Isolation by distance of aquatic plants is expected to be stronger across than alongside mountain ridges whereas the heterogeneity of habitats among populations and temporary droughts may influence connectivity and hamper dispersal. Suitable aquatic plant habitats became reduced, even for the widespread submerged Potamogeton pectinatus L. (also named Stuckenia pectinata) giving structure to various aquatic habitats. We compared the level of genetic diversity in a heterogeneous series of aquatic habitats across Iran and tested their differentiation over distances and across mountain ranges (Alborz and Zagros) and desert zones (Kavir), with values obtained from temperate region populations. The diversity of aquatic ecosystems across and along large geographic barriers provided a unique ecological situation within Iran. P. pectinatus were considered from thirty-six sites across Iran at direct flight distances ranging from 20 to 1,200 km. Nine microsatellite loci revealed a very high number of alleles over all sites. A PCoA, NJT clustering and STRUCTURE analysis revealed a separate grouping of individuals of southeastern Iranian sites and was confirmed by their different nuclear ITS and cpDNA haplotypes thereby indicating an evolutionary significant unit (ESU). At the level of populations, a positive correlation between allelic differentiation Dest with geographic distance was found. Individual-based STRUCTURE analysis over 36 sites showed 7 genetic clusters. FST and RST values for ten populations reached 0.343 and 0.521, respectively thereby indicating that allele length differences are more important and contain evolutionary information. Overall, higher levels of diversity and a stronger differentiation was revealed among

Removal of the radioactive materials from the trench submergence in Fukushima

International Nuclear Information System (INIS)

Okita, Takeshi; Ikeda, Akira; Oomura, Hisao; Kojima, Chiaki; Nozawa, Keiji

2014-01-01

Toshiba has been contributing for stabilization from the accident of Fukushima Daiichi nuclear power plant. One of the contribution areas is the treatment of highly contaminated water accumulated in the piping trench of Unit 2 and Unit 3. As an emergency countermeasure, Toshiba installed the mobile type water treatment system which is named SMARTS (Simplified Mobile Adsorption and Retrieve for Trench Submergence) for removal of radionuclide. SMARTS has achieved 10 3 ∼ 10 4 decontamination factor (DF) for Cesium (Cs) in the actual operation. This paper describes the formation of SMARTS and the result of performance. (author)

Assessment of Wetland Water Quality and Avian Diversity of a Human-Modified Floodplain Wetland on River Yamuna

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Upma MANRAL

2013-02-01

Full Text Available Okhla Bird Sanctuary (OBS is an Important Bird Area, which comes under the protected area network of Uttar Pradesh with one-third area lying in the state of Delhi (India. OBS has widest flood plains along the Delhi stretch of river Yamuna and is important in conserving the ecological wealth of floodplains of the river. Rapid urbanization and industrialization and discharge of untreated wastewater into the river have resulted in deteriorated water quality. The present study focused on assessment of water quality, aquatic flora and avifaunal diversity in the OBS. Water quality was analyzed following methods of APHA. For vegetation analysis, sub-merged and free-floating plants were scooped up from five randomly selected sites. Total bird counts were conducted for water birds and species richness, evenness and Shannon-Weaver species diversity indices were calculated. Results indicate that the organic load is very high in the wetland as evident from low levels of dissolved oxygen (2.26 ± 1.62 mg/l and high Biological and Chemical Oxygen Demands (15.20 ± 3.75 mg/l, 44.60 ± 12.07 mg/l. Nine species of free-floating and submerged plants were recorded; Hydrilla verticillata, Vallisneria spiralis, Azolla pinnata and Ceratophyllum demersum dominated both deep and shallow water areas. 52 species of waterbirds including four near-threatened species viz., Anhinga melanogaster, Mycteria leucocephala, Threskiornis melanocephalus and Aythya nyroca were recorded. OBS provides opportunities for conservation in a metropolitan area, thus, appropriate measures should be taken to maintain its ecological integrity.

Underwater photosynthesis in flooded terrestrial plants: a matter of leaf plasticity

NARCIS (Netherlands)

Mommer, L.; Visser, E.J.W.

2005-01-01

• Background Flooding causes substantial stress for terrestrial plants, particularly if the floodwater completely submerges the shoot. The main problems during submergence are shortage of oxygen due to the slow diffusion rates of gases in water, and depletion of carbohydrates, which is the substrate

Canopy Modeling of Aquatic Vegetation: Construction of Submerged Vegetation Index

Science.gov (United States)

Ma, Z.; Zhou, G.

2018-04-01

The unique spectral characteristics of submerged vegetation in wetlands determine that the conventional terrestrial vegetation index cannot be directly employed to species identification and parameter inversion of submerged vegetation. Based on the Aquatic Vegetation Radiative Transfer model (AVRT), this paper attempts to construct an index suitable for submerged vegetation, the model simulated data and a scene of Sentinel-2A image in Taihu Lake, China are utilized for assessing the performance of the newly constructed indices and the existent vegetation indices. The results show that the angle index composed by 525 nm, 555 nm and 670 nm can resist the effects of water columns and is more sensitive to vegetation parameters such as LAI. Furthermore, it makes a well discrimination between submerged vegetation and water bodies in the satellite data. We hope that the new index will provide a theoretical basis for future research.

Development of New Submergence Tolerant Rice Variety for Bangladesh Using Marker-Assisted Backcrossing

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Khandakar Md Iftekharuddaula

2015-01-01

Full Text Available Submergence tolerant high yielding rice variety was developed using BR11 as a recipient parent applying foreground, phenotypic and background selection approaches. Recombinant selection was found essential to minimize linkage drag by BC2F2 generation. Without recombinant selection, the introgression size in the backcross recombinant lines (BRLs was approximately 15 Mb on the carrier chromosome. The BRLs were found submergence tolerance compared to the check varieties under complete submergence for two weeks at Bangladesh Rice Research Institute, and produced higher yield compared to the isogenic Sub1-line under controlled submerged condition. The BRL IR85260-66-654-Gaz2 was released as BRRI dhan52 in 2010, which was the first high yielding submergence tolerant variety in Bangladesh. BRRI dhan52 produced grain yield ranging from 4.2 to 5.2 t/hm2 under different flash flood prone areas of Bangladesh in three consecutive seasons. The study demonstrated the efficiency of recombinant selection and better adaptability of the newly released submergence tolerant high yielding variety in flash flood prone different areas of the country with respect to submergence tolerance and yield potential.

Vibrational analysis of submerged cylindrical shells based on elastic foundations

International Nuclear Information System (INIS)

Shah, A.G.; Naeem, M.N.

2014-01-01

In this study a vibration analysis was performed of an isotropic cylindrical shell submerged in fluid, resting on Winkler and Pasternak elastic foundations for simply supported boundary condition. Love's thin shell theory was exploited for strain- and curvature- displacement relationship. Shell problem was solved by using wave propagation approach. Influence of fluid and Winkler as well as Pasternak elastic foundations were studied on the natural frequencies of submerged isotropic cylindrical shells. Results were validated by comparing with the existing results in literature. Vibration, Submerged cylindrical shell, Love's thin shell theory, Wave propagation method, Winkler and Pasternak foundations. (author)

Distribution and abundance of submerged aquatic macrophytes in a reactor cooling reservoir

Energy Technology Data Exchange (ETDEWEB)

Grace, J.B.

1977-08-01

Measurements of ash-free dry weight were used to characterize the effects of a heated effluent on submerged macrophytes in a reactor cooling reservoir. The species which were most abundant during the summers of 1974 and 1975 were Myriophyllum spicatum L. and Eleocharis acicularis (L.) R. and S. Examination of the vertical distribution of the shoot biomass of Myriophyllum revealed that plants in heated areas grew closer to the water surface than plants in unheated areas. The biomass of the second most abundant species, Eleocharis acicularis, was less at 0.5 m depths in heated areas (more than 5C/sup 0/ warmer than unheated areas) than at equal depths in unheated areas. Species diversity was greater at heated locations because of a greater equitability (i.e., evenness of distribution of biomass) among species.

Decomposition characteristics of three different kinds of aquatic macrophytes and their potential application as carbon resource in constructed wetland.

Science.gov (United States)

Wu, Suqing; He, Shengbing; Zhou, Weili; Gu, Jianya; Huang, Jungchen; Gao, Lei; Zhang, Xu

2017-12-01

Decomposition of aquatic macrophytes usually generates significant influence on aquatic environment. Study on the aquatic macrophytes decomposition may help reusing the aquatic macrophytes litters, as well as controlling the water pollution caused by the decomposition process. This study verified that the decomposition processes of three different kinds of aquatic macrophytes (water hyacinth, hydrilla and cattail) could exert significant influences on water quality of the receiving water, including the change extent of pH, dissolved oxygen (DO), the contents of carbon, nitrogen and phosphorus, etc. The influence of decomposition on water quality and the concentrations of the released chemical materials both followed the order of water hyacinth > hydrilla > cattail. Greater influence was obtained with higher dosage of plant litter addition. The influence also varied with sediment addition. Moreover, nitrogen released from the decomposition of water hyacinth and hydrilla were mainly NH 3 -N and organic nitrogen while those from cattail litter included organic nitrogen and NO 3 - -N. After the decomposition, the average carbon to nitrogen ratio (C/N) in the receiving water was about 2.6 (water hyacinth), 5.3 (hydrilla) and 20.3 (cattail). Therefore, cattail litter might be a potential plant carbon source for denitrification in ecological system of a constructed wetland. Copyright © 2017 Elsevier Ltd. All rights reserved.

Improved flooding tolerance and carbohydrate status of flood-tolerant plant Arundinella anomala at lower water temperature.

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Xiao Qi Ye

Full Text Available Operation of the Three Gorges Reservoir (TGR, China imposes a new water fluctuation regime, including a prolonged winter submergence in contrast to the natural short summer flooding of the rivers. The contrasting water temperature regimes may remarkably affect the survival of submerged plants in the TGR. Plant survival in such prolonged flooding might depend on the carbohydrate status of the plants. Therefore, we investigated the effects of water temperature on survival and carbohydrate status in a flood-tolerant plant species and predicted that both survival and carbohydrate status would be improved by lower water temperatures.A growth chamber experiment with controlled water temperature were performed with the flood-tolerant species Arundinella anomala from the TGR region. The plants were submerged (80 cm deep water above soil surface with a constant water temperature at 30°C, 20°C or 10°C. The water temperature effects on survival, plant biomass and carbohydrate content (glucose, fructose and sucrose and starch in the viable and dead tissues were investigated.The results showed that the survival percentage of A.anomala plants was greatly dependent on water temperature. The two-month submergence survival percentage was 100% at 10°C, 40% at 20°C and 0% at 30°C. Decreasing the water temperature led to both later leaf death and slower biomass loss. Temperature decrease also induced less reduction in glucose, fructose and sucrose in the roots and leaves (before decay, p 0.05. Different water temperatures did not alter the carbon pool size in the stems, leaves and whole plants (p > 0.05, but a clear difference was found in the roots (p < 0.05, with a larger pool size at a lower temperature.We concluded that (1 A. anomala is characterized by high flooding tolerance and sustained capability to mobilize carbohydrate pool. (2 The survival percentage and carbohydrate status of submerged A. anomala plants were remarkably improved by lower water

Heat transfer study of a submerged reactor channel under boil-off condition

Energy Technology Data Exchange (ETDEWEB)

Mukhopadhyay, Deb [Bhabha Atomic Research Centre, Mumbai (India). Reactor Safety Div.; Sahoo, P.K. [Indian Institute of Technology, Roorkee (India). Dept. of Mechanical and Industrial Engineering; Ghosh, A.K. [Bhabha Atomic Research Centre, Mumbai (India). Health, Safety and Environment Group

2012-12-15

Experiments have been carried out to study the heatup behavior of a single segmented reactor channel for Pressurized Heavy Water Reactor under submerged, partially submerged and exposed conditions. This situation may arise from a severe accident scenario of Pressurised Heavy Water Reactors where full or segmented reactor channels are likely to be disassembled and form a submerged debris bed. An assembly of electrical heater rod, simulating fuel bundle and channel components like Pressure Tube and Calandria Tube constitutes the segmented reactor channel. Heatup of this assembly is observed with respect to different water levels ranging from full submergence to totally exposed and power levels of 6-8 kW, typical to decay power level. It has been observed from the set of experiment that fuel bundle local dry out followed by heatup does not happen till the bundle is partially submerged. Temperature excursion of the bundle is evident when the bundle is exposed to steam-air environment. (orig.)

The grain boundary segregation of phosphorus in thermally aged and irradiated C-Mn submerged-are weld metal

International Nuclear Information System (INIS)

Mendes, C.M.

1999-01-01

The segregation of free phosphorus atoms to grain boundaries in C-Mn steels has been identified as an embrittlement mechanism. A change in the brittle fracture mechanism from transgranular to intergranular has been observed for materials with higher phosphorus grain boundary coverage. The grain boundary segregation of phosphorus in various steels used in the nuclear power industry has been thermodynamically and kinetically modelled mostly with the Langmuir-McLean model. Recent publications have also suggested that neutron irradiation can affect segregation and various attempts at modelling this are currently under way. The present paper describes a data base assembled on phosphorus grain boundary coverage measured by Auger electron spectroscopy on thermally aged and irradiated C-Mn submerged-arc weld specimens. Software tools were developed to evaluate the changes in phosphorus grain boundary coverage associated with instantaneous temperature changes and temperature gradients. The phosphorus free energy change associated with grain boundary segregation was modelled from the thermally aged data and used with the software to determine the phosphorus segregation in submerged-arc weld metals following the post weld stress relief heat treatments received prior to plant operation. The phosphorus grain boundary coverage changes arising from the thermal history of submerged-arc weld materials during irradiation were also modelled and found to compare well with data obtained on irradiated materials. It was concluded that under the irradiation conditions sampled, phosphorus grain boundary segregation in submerged-arc weld materials can be modelled successfully using only the thermal term without appealing to an irradiation induced segregation process. (author)

THE STUDY ON THE DURABILITY OF SUBMERGED STRUCTURE DISPLACEMENT DUE TO CONCRETE FAILURE

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M. Mohd

2016-09-01

Full Text Available Concrete structures that exposed to marine environments are subjected to multiple deterioration mechanisms. An overview of the existing technology for submerged concrete, pressure resistant, concrete structures which related such as cracks, debonds, and delamination are discussed. Basic knowledge related to drowning durability such as submerged concrete structures in the maritime environment are the durability of a concrete and the ability to resist to weathering, chemical attack, abrasion or other deterioration processes. The measuring techniques and instrumentation for geometrical monitoring of submerged structural displacements have traditionally been categorized into two groups according to the two main groups, namely as geodetic surveying and geotechnical structural measurements of local displacements. This paper aims to study the durability of submerged concrete displacement and harmful effects of submerged concrete structures.

Demonstration and Field Evaluation of Streambank Stabilization with Submerged Vanes

Science.gov (United States)

Whitman, H.; Hoopes, J.; Poggi, D.; Fitzpatrick, F.; Walz, K.; ,

2001-01-01

The effectiveness of submerged vanes for reducing bank erosion and improving aquatic habitat is being evaluated at a site on North Fish Creek, a Lake Superior tributary. Increased runoff from agricultural areas with clayey soils has increased flood magnitudes and the erosion potential/transport capacity of the stream. Most of the creek's sediment load originates from the erosion of 17 large bluffs. This creek contains important recreational fisheries that are potentially limited by the loss of aquatic habitat from deposition of sediment on spawning beds. Submerged vanes are a cost effective and environmentally less intrusive alternative to traditional structural stabilization measures. Submerged vanes protrude from a channel bed, are oriented at an angle to the local velocity, and are distributed along a portion of channel. They induce a transverse force and torque on the flow along with longitudinal vortexes that alter the cross sectional shape and alignment of the channel. Submerged vanes were installed at a bluff/bend site in summer and fall 2000. The number, size, and layout of the vanes were based upon the channel morphology under estimated bankfull conditions. The effectiveness of the vanes will be evaluated by comparing surveys of the bluff face, streamflow, and channel conditions for several years after installation of the submerged vanes with surveys before and immediately after their installation.

Effect of inorganic nutrients on relative contributions of fungi and bacteria to carbon flow from submerged decomposing leaf litter

Science.gov (United States)

Vladislav Gulis; Keller Suberkropp

2003-01-01

The relative contributions of fungi and bacteria to carbon flow from submerged decaying plant litter at different levels of inorganic nutrients (N and P) were studied. We estimated leaf mass loss, fungal and bacterial biomass and production, and microbial respiration and constructed partial carbon budgets for red maple leaf disks precolonized in a stream and then...

Wastewater treatment with submerged fixed bed biofilm reactor systems--design rules, operating experiences and ongoing developments.

Science.gov (United States)

Schlegel, S; Koeser, H

2007-01-01

Wastewater treatment systems using bio-films that grow attached to a support media are an alternative to the widely used suspended growth activated sludge process. Different fixed growth biofilm reactors are commercially used for the treatment of municipal as well as industrial wastewater. In this paper a fairly new fixed growth biofilm system, the submerged fixed bed biofilm reactor (SFBBR), is discussed. SFBBRs are based on aerated submerged fixed open structured plastic media for the support of the biofilm. They are generally operated without sludge recirculation in order to avoid clogging of the support media and problems with the control of the biofilm. Reactor and process design considerations for these reactors are reviewed. Measures to ensure the development and maintenance of an active biofilm are examined. SFBBRs have been applied successfully to small wastewater treatment plants where complete nitrification but no high degree of denitrification is necessary. For the pre-treatment of industrial wastewater the use of SFBBRs is advantageous, especially in cases of wastewater with high organic loading or high content of compounds with low biodegradability. Performance data from exemplary commercial plants are given. Ongoing research and development efforts aim at achieving a high simultaneous total nitrogen (TN) removal of aerated SFBBRs and at improving the efficiency of TN removal in anoxic SFBBRs.

New methods for the analysis of invasion processes: multi-criteria evaluation of the invasion of Hydrilla verticillata in Guatemala.

Science.gov (United States)

Monterroso, I; Binimelis, R; Rodríguez-Labajos, B

2011-03-01

The study described in this article incorporates stakeholders' views on aquatic invasion processes and combines expert analysis with information from field work into an evaluation exercise. Management scenarios are designed based on available technical data and stakeholders' perceptions. These scenarios are evaluated using the Social Multi-Criteria Evaluation framework employing the NAIADE model. Two evaluations are carried out, technical and social. Social acceptance of different management scenarios, distribution of costs and benefits, and attribution of responsibility are discussed. The case study was carried out on Lake Izabal, a body of water connected to the Caribbean Sea in Northeastern Guatemala. In 2000, local fishermen reported the presence of an alien species in the lake, the macrophyte Hydrilla verticillata. Two years later, this alien species was established around the entire lakeshore, damaging the ecosystem, endangering native species and the subsistence of local inhabitants through impacts on transportation, fishing practices, and tourism. Copyright © 2010 Elsevier Ltd. All rights reserved.

Effective mass and damping of submerged structures

International Nuclear Information System (INIS)

Dong, R.G.

1978-01-01

Various structures important for safety in nuclear power plants must remain functioning in the event of an earthquake or other dynamic phenomenon. Some of these important structures, such as spent-fuel storage racks, main pressure-relief valve lines, and internal structures in the reactor vessel, are submerged in water. Dynamic analysis must include the force and damping effects of water. This report provides a technical basis for evaluating the wide variety of modeling assumptions currently used in design analysis. Current design analysis techniques and information in the literature form the basis of our conclusions and recommendations. We surveyed 32 industrial firms and reviewed 49 technical references. We compare various theories with published experimental results wherever possible. Our findings generally pertain to idealized structures, such as single isolated members, arrays of members, and coaxial cylinders. We relate these findings to the actual reactor structures through observations and recommendations. Whenever possible we recommend a definite way to evaluate the effect of hydrodynamic forces on these structures

Submergence sensitivity of durum wheat, bread wheat and barley at the germination stage

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Iduna Arduini

2016-06-01

Full Text Available Soil waterlogging at initial growth stages can cause heavy yield losses of winter cereals. Therefore, the screening for submergence tolerance traits in seeds of commercial varieties is of high concern worldwide. Ten Italian varieties of durum wheat (Triticum durum Desf., bread wheat (T. aestivum L. and barley (Hordeum vulgare L. were investigated for their ability to germinate in submerged conditions and to recover after submergence periods of three to 15 days. Submergence prevented germination and decreased germinability, at rates that increased with duration of submergence. Sensitivity ranked in the order: barley >durum wheat >bread wheat. We related the higher sensitivity of barley to its slower germination and slightly higher leakage of electrolytes, whereas the percentage of abnormal seedlings was lower than in other species. It was less than 4%, compared to less than 15 and 8% in durum wheat and bread wheat, respectively. Wide varietal differences were found in all species. According to variety, after 6-day submergence, germinability ranged from 2 to 42% in barley, from 5 to 80% in durum wheat, and from 30 to 77% in bread wheat. Varieties with more than 40% seed survival were three, six and seven per species, in the same order. The differential submergence sensitivity of varieties indicates a potential to select for waterlogging tolerance within Italian genotypes of winter cereal crops.

Safe shutdown analysis for submerged equipment inside containment

International Nuclear Information System (INIS)

Song, Dong Soo; Lee, Seung Chan; Yoon, Duk Joo; Ha, Sang Jun

2017-01-01

The purpose of the paper is to analyze internal flooding effects on the submerged safety-related components inside containment building. Safe shutdown analysis has been performed based on the criteria, assumptions and guideline provided in ANSI/ANS-56.11-1988 and ANSI/ANS-58.11-1988. Flooding can be postulated from a failure of several systems located inside the containment. Loss of coolant accident (LOCA), Feed water line break (FWLB), and other pipe breaks/cracks are assumed. The worst case flooding scenario is a large break LOCA. The maximum flood level for a large break LOCA is calculated based on the combined inventory of the reactor coolant system, the three accumulators, the boron injection tank (BIT), the chemical additive tank (CAT), and the refueling water storage tank (RWST) flooding the containment. The maximum flood level that could occur from all of the water which is available in containment is 2.3 m from the base elevation. A detailed flooding analysis for the components has been performed to demonstrate that internal flooding resulting from a postulated initiating event does not cause the loss of equipment required to achieve and maintain safe shutdown of the plant, emergency core cooling capability, or equipment whose failure could result in unacceptable offsite radiological consequences. The flood height can be calculated as h = (dh/dt) x (t-t 0 ) + h 0 , where h = time dependent flood height and subscript 0 means the initial value and height slope dh/dt. In summary, the submerged components inside containment are acceptable because they complete the mission of safety injection (SI) prior to submeregency or have no safe shutdown function including containment isolation during an accident. (author)

Studies on sustainability of simulated constructed wetland system for treatment of urban waste: Design and operation.

Science.gov (United States)

Upadhyay, A K; Bankoti, N S; Rai, U N

2016-03-15

New system configurations and wide range of treatability make constructed wetland (CW) as an eco-sustainable on-site approach of waste management. Keeping this view into consideration, a novel configured three-stage simulated CW was designed to study its performance efficiency and relative importance of plants and substrate in purification processes. Two species of submerged plant i.e., Potamogeton crispus and Hydrilla verticillata were selected for this study. After 6 months of establishment, operation and maintenance of simulated wetland, enhanced reduction in physicochemical parameters was observed, which was maximum in the planted CW. The percentage removal (%) of the pollutants in three-stage mesocosms was; conductivity (60.42%), TDS (67.27%), TSS (86.10%), BOD (87.81%), NO3-N (81.28%) and PO4-P (83.54%) at 72 h of retention time. Submerged macrophyte used in simulated wetlands showed a significant time dependent accumulation of toxic metals (p ≤ 0.05). P. crispus accumulated the highest Mn (86.36 μg g(-1) dw) in its tissue followed by Cr (54.16 μg g(-1) dw), Pb (31.56 μg g(-1) dw), Zn (28.06 μg g(-1) dw) and Cu (25.76 μg g(-1) dw), respectively. In the case of H. verticillata, it was Zn (45.29), Mn (42.64), Pb (22.62), Cu (18.09) and Cr (16.31 μg g(-1) dw). Thus, results suggest that the application of simulated CW tackles the water pollution problem more efficiently and could be exploited in small community level as alternative and cost effective tools of phytoremediation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Metal accumulation by submerged macrophytes in eutrophic lakes at the watershed scale.

Science.gov (United States)

Xing, Wei; Wu, Haoping; Hao, Beibei; Liu, Guihua

2013-10-01

Metal concentrations (Al, Ba, Ca, K, Li, Mg, Na, Se, Sr and Ti) in submerged macrophytes and corresponding water and sediments were studied in 24 eutrophic lakes along the middle and lower reaches of the Yangtze River (China). Results showed that these eutrophic lakes have high metal concentrations in both water and sediments because of human activities. Average concentrations of Al and Na in tissues of submerged macrophytes were very high in sampled eutrophic lakes. By comparison, Ceratophyllum demersum and Najas marina accumulated more metals (e.g. Ba, Ca, K, Mg, Na, Sr and Ti). Strong positive correlations were found between metal concentrations in tissues of submerged macrophytes, probably because of co-accumulation of metals. The concentrations of Li, Mg, Na and Sr in tissues of submerged macrophytes significantly correlated with their corresponding water values, but not sediment values.

Long-term allelopathic control of phytoplankton by the submerged macrophyte Elodea nuttallii

NARCIS (Netherlands)

Vanderstukken, M.; Declerck, S.A.J.; Decaestecker, E.; Muylaert, K.

2014-01-01

Keywords: allelochemicals; chemical ecology; competition; nutrient limitation; shallow lakes Summary 1.It is well known that submerged macrophytes can suppress phytoplankton blooms in lakes and thus promote water quality and biodiversity. One of the possible mechanisms through which submerged

Effect of organic matter on the uptake of phosphorus by rice plants under different moisture conditions

International Nuclear Information System (INIS)

Ghosh, Geetanjali

1974-01-01

In studies on the effect of three levels of moisture and two levels of organic matter in two alluvial soils, the uptake of P by rice plant both from soil and fertilizer sources was the highest and Eh the lowest under submerged conditions. No marked difference in total uptake of P was observed in upland and alternate submerged condition; organic matter application showed an appreciable effect under submerged condition. (author)

Topology optimization for submerged buoyant structures

NARCIS (Netherlands)

Picelli, R.; van Dijk, R.; Vicente, W.M.; Pavanello, R.; Langelaar, M.; van Keulen, A.

2017-01-01

This paper presents an evolutionary structural topology optimization method for the design of completely submerged buoyant modules with design-dependent fluid pressure loading. This type of structure is used to support offshore rig installation and pipeline transportation at all water depths. The

Periphyton density is similar on native and non-native plant species

NARCIS (Netherlands)

Grutters, B.M.C.; Gross, Elisabeth M.; van Donk, E.; Bakker, E.S.

2017-01-01

Non-native plants increasingly dominate the vegetation in aquatic ecosystems and thrive in eutrophic conditions. In eutrophic conditions, submerged plants risk being overgrown by epiphytic algae; however, if non-native plants are less susceptible to periphyton than natives, this would contribute to

Development of spent solvent treatment process by a submerged combustion technique

International Nuclear Information System (INIS)

Uchiyama, Gunzo; Maeda, Mitsuru; Fujine, Sachio; Amakawa, Masayuki; Uchida, Katsuhide; Chida, Mitsuhisa

1994-01-01

An experimental study using a bench-scale equipment of 1 kg-simulated spent solvents per hour has been conducted in order to evaluate the applicability of a submerged combustion technique to the treatment of spent solvents contaminated with TRU elements. This report describes the experimental results on the combustion characteristics of the simulated spent solvents of tri-n-butyl phosphate and/or n-dodecane, and on the distribution behaviors of combustion products such as phosphoric acid, Ru, I, Zr and lanthanides as TRU simulants in the submerged combustion process. Also the experimental results of TRU separation from phosphoric acid solution by co-precipitation using bismuth phosphate are reported. It was shown that the submerged combustion technique was applicable to the treatment of spent solvents including the distillation residues of the solvent. Based on the experimental data, a new treatment process of spent solvent was proposed which consisted of submerged combustion, co-precipitation using bismuth phosphate, ceramic membrane filtration, cementation of TRU lean phosphate, and vitrification of TRU rich waste. (author)

Could artificial plant beds favour microcrustaceans during biomanipulation of eutrophic shallow lakes?

DEFF Research Database (Denmark)

Balayla, David; Boll, Thomas; Trochine, Carolina

2017-01-01

Introduction of artificial plants may facilitate the transition from a turbid to a clear-water state in shallow lakes, particularly when plant establishment is delayed. We investigated the usefulness of artificial plants as a restoration tool in an experimental setup mimicking open submerged plant...

Pump Coastdown with the Submerged Flywheel

Energy Technology Data Exchange (ETDEWEB)

Yoon, Hyun-Gi; Seo, KyoungWoo; Kim, Seong Hoon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

Many research reactors are generally designed as open pool types in consideration of the heat removal of the nuclear fuels, reactor operation and accessibility. Reactor structure assembly is generally placed at the pool bottom as shown in Fig. 1. Primary cooling system pump circulates the coolant from the reactor structure to the heat exchanger in order to continuously remove the heat generated from the reactor core in the research reactor as shown in Fig. 1. The secondary cooling system releases the transferred heat to the atmosphere by the cooling tower. Coastdown flow rate of the primary cooling system pump with the submerged flywheel are calculated analytically in case of the accident situation. Coastdown flow rate is maintained until almost 80 sec when the pump stops normally. But, coastdown flow rate is rapidly decreased when the flywheel is submerged because of the friction load on the flywheel surface.

Using algae and submerged calcifying water flora for treating neutral to alkaline uranium-contaminated water

International Nuclear Information System (INIS)

Dienemann, C.; Dienemann, H.; Stolz, L.; Dudel, E.G.

2005-01-01

Elimination of uranium from neutral to alkaline water is a complex technical process involving decarbonation, usually with HCl, followed by uranium removal by adding alkaline substances. In passive water treatment systems, uranium species - which often consist of a combination of oxidation and reduction stages - are not sufficiently considered. Algae and submerged water plants provide a natural alternative. They remove carbon dioxides or hydrogen carbonate, depending on the species, thus reducting the concentrations of the carbonate species. As the uranium species in alkaline water are coupled on the one hand to the carbonate species and on the other hand on the earth alkali metals, algae and submerged calcifying water plants are an excellent preliminary stage as a supplement to conventional passive water treatment systems. For a quantification of this effect, laboratory experiments were made with Cladophara spec. and with uranium concentrations of 100, 250 and 1000 μg U.L -1 at pH 8.3. The pH was adjusted with NaOH resp. Na2CO3 resulting in different uranium species. After 20 minutes, there was a difference in self-absorption between the different species (higher uranium concentration for NaOH than for Na2CO3), which was no longer observeable after 24 h. On the basis of data on the biomass development of macrophytic algae (Cladophora and Microspora) in a flowing river section near Neuensalz/Vogtland district, the final dimensions of a purification stage of this type are assessed. (orig.)

Influence of Microalgae onto submerged surfaces on Fouling

Science.gov (United States)

Kong, M.; Eom, C.; Yoon, B.; Yoon, H.; Kim, B.; Chung, K.

2012-12-01

Lots of algae together with organic matter deposited on the submerged surface can be easily observed occurring in the shallower water along the coast. This is mainly because only those organisms with the ability to adapt to the new situations created by man can firmly adhere enough to avoid being washed off. Chemical and microbiological characteristics of the fouling microalgae developed on various surfaces in contact with the seawater were made. The microbial compositions of the microalgae formed on the submerged surfaces were tested for. The quantities of the diverse microalgae in the samples developed on the prohibiting submerged surface were larger when there was no concern about materials for special selection for fouling. To confirm formation of microalgae on adsorbents was done SEM-EDS (Scanning Electron Microscope-Spectrometer) analysis. Microbial identified using optical microscope. In addition to, we quantified attaching microalgae as pass time. Experiment results, ten species which are Nitzshhia sp., Eucampia sp., Coscinodiscus sp., Licmophora sp., Rhizosolenia sp., Cylindrotheca sp., Striateela sp., Thalassionema sp., Guinardia sp., and Helicostomella sp. discovered to reservoir formed biofouling. They showed the important role microbial activity in fouling and corrosion of the surfaces in contact with the any seawater.

Rice SUB1A constrains remodeling of the transcriptome and metabolome during submergence and post-submergence recovery”.

Science.gov (United States)

The rice (Oryza sativa L.) ethylene-responsive transcription factor SUB1A confers tolerance to prolonged, complete submergence by limiting underwater elongation growth. Rice encoding SUB1A-1 also recovers photosynthetic function and re-commences development towards flowering more rapidly after desu...

An ultrasonic method for separation of epiphytic microbes from freshwater submerged macrophytes.

Science.gov (United States)

Cai, Xianlei; Gao, Guang; Yang, Jing; Tang, Xiangming; Dai, Jiangyu; Chen, Dan; Song, Yuzhi

2014-07-01

Epiphytic microbes are common inhabitants of freshwater submerged macrophytes, which play an important role in aquatic ecosystems. An important precondition for studying the epiphytic microbes is having an effective method of separating the attached microbes from the host macrophytes. We developed an ultrasound-based method for separating epiphytic microbes from freshwater submerged macrophytes, optimized the conditions of ultrasonic separation with an orthogonal experimental design, and compared the optimized ultrasonic method with manual separation. This method can be particularly useful for freshwater submerged macrophytes having a complex morphology. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Application of submerged induction hardening; Ekichu koshuha yakiire no jitsuyoka

Energy Technology Data Exchange (ETDEWEB)

Nishimori, Y; Nagai, Y; Amii, Y [Mazda Motor Corp., Hiroshima (Japan); Tanaka, Y [Netsuren Co. Ltd., Tokyo (Japan); Mizuma, T [Toyo Advanced Technologies Co. Ltd., Hiroshima (Japan)

1997-10-01

As a cost-cutting measure, the linerless diesel engine was adopted by applying submerged induction hardening process which can harden partial inner surface of cylinder block bore. In applying this process, (1) development of induction coil which can form any shape of quenched pattern and (2) the development of machining technology which can hone precisely the distorted bore after quenching, were important. With these improvements, submerged Induction hardening was made practical. 1 ref., 11 figs.

Uptake and elimination kinetics of perfluoroalkyl substances in submerged and free-floating aquatic macrophytes: Results of mesocosm experiments with Echinodorus horemanii and Eichhornia crassipes.

Science.gov (United States)

Pi, N; Ng, J Z; Kelly, B C

2017-06-15

Studies investigating the bioaccumulation behavior of perfluoroalkyl substances (PFASs) in aquatic macrophytes are limited. The present study involved controlled mesocosm experiments to assess uptake and elimination rate constants (k u, k e ), bioconcentration factors (BCFs) and translocation factors (TFs) of several perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs) in two aquatic plant species, including one submerged species (Echinodorus horemanii) and one free-floating species (Eichhornia crassipes). The results indicated all PFASs were readily accumulated in these aquatic macrophytes. k u and BCFs increased with increasing perfluoroalkyl chain length. For PFCAs and PFSAs with identical perfluoroalkyl chain length, the corresponding PFSA exhibited higher bioaccumulation potential. On a whole-plant basis, the bioaccumulation potential of PFASs in submerged and free-floating macrophytes were comparable, indicating sorption to plant biomass is similar in the different species. Conversely, when considering accumulation in foliage, BCFs in the free-floating macrophyte were substantially lower compared to submerged species, especially for longer-chain PFASs. Compounds with shorter perfluoroalkyl chain length (PFBS, PFPeA and PFHxA) exhibited preferential translocation to leaf tissue (TFs >1). BCFs exhibited a sigmoidal relationship with pefluoroalkyl chain length, membrane-water distribution coefficients (D mw ), protein-water distribution coefficients (D pw ) and organic-water partition coefficients (K oc ). For these trends, maximum BCF values were exhibited by long-chain PFCAs, with a log D mw , log D pw and log K oc of 6.47, 5.72 and 5.04, respectively. These findings are useful for future design and implementation of phytoremediation systems, as well for future develop of mechanistic models for predicting the environmental fate and distribution of these contaminants of concern. Copyright © 2017. Published by Elsevier Ltd.

Prediction of Heat Removal Capacity of Horizontal Condensation Heat Exchanger submerged in Pool

Energy Technology Data Exchange (ETDEWEB)

Jeon, Seong-Su; Hong, Soon-Joon [FNC Tech., Yongin (Korea, Republic of); Cho, Hyoung-Kyu [Seoul National University, Seoul (Korea, Republic of); Park, Goon-Cherl [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

2014-10-15

As representative passive safety systems, there are the passive containment cooling system (PCCS) of ESBWR, the emergency condenser system (ECS) of the SWR-1000, the passive auxiliary feed-water system (PAFS) of the APR+ and etc. During the nuclear power plant accidents, these passive safety systems can cool the nuclear system effectively via the heat transfer through the steam condensation, and then mitigate the accidents. For the optimum design and the safety analysis of the passive safety system, it is essential to predict the heat removal capacity of the heat exchanger well. The heat removal capacity of the horizontal condensation heat exchanger submerged in a pool is determined by a combination of a horizontal in-tube condensation heat transfer and a boiling heat transfer on the horizontal tube. Since most correlations proposed in the previous nuclear engineering field were developed for the vertical tube, there is a certain limit to apply these correlations to the horizontal tube. Therefore, this study developed the heat transfer model for the horizontal Ushaped condensation heat exchanger submerged in a pool to predict well the horizontal in-tube condensation heat transfer, the boiling heat transfer on the horizontal tube and the overall heat removal capacity of the heat exchanger using the best-estimate system analysis code, MARS.

The maximization of the productivity of aquatic plants for use in controlled ecological life support systems (CELSS)

Science.gov (United States)

Thompson, B. G.

Lemna minor (common duckweed) and a Wolffia sp. were grown in submerged growth systems. Submerged growth increased the productivity/unit volume (P/UV) of the organisms and may allow these plants to be used in a controlled ecological life support system (CELSS).

Differential Response of Floating and Submerged Leaves of Longleaf Pondweed to Silver Ions

Directory of Open Access Journals (Sweden)

Nisha Shabnam

2017-06-01

Full Text Available In this study, we have investigated variations in the potential of floating and submerged leaves of longleaf pondweed (Potamogeton nodosus to withstand silver ion (Ag+-toxicity. Both floating and submerged leaves changed clear colorless AgNO3 solutions to colloidal brown in the presence of light. Transmission electron microscopy revealed the presence of distinct crystalline Ag-nanoparticles (Ag-NPs in these brown solutions. Powder X-ray diffraction pattern showed that Ag-NPs were composed of Ag0 and Ag2O. Photosystem (PS II efficiency of leaves declined upon exposure to Ag+ with a significantly higher decline in the submerged leaves than in the floating leaves. Similarly, Ag+ treatment caused a significant reduction in the carboxylase activity of the ribulose bisphosphate carboxylase/oxygenase in leaves. The reduction in this carboxylase activity was significantly higher in the submerged than in the floating leaves. Ag+ treatment also resulted in a significant decline in the levels of non-enzymatic and enzymatic antioxidants; the decline was significantly lower in the floating than in submerged leaves. X-ray photoelectron spectroscopy revealed the presence of Ag2O in these leaves. Inductively coupled plasma mass spectrometry analysis revealed a three-fold higher Ag content in the submerged than in floating leaves. Our study demonstrates that floating leaves of longleaf pondweed have a superior potential to counter Ag+-toxicity compared with submerged leaves, which could be due to superior potential of floating leaves to reduce Ag+ to less/non-toxic Ag0/Ag2O-nanoparticles/nanocomplexes. We suggest that modulating the genotype of longleaf pondweed to bear higher proportion of floating leaves would help in cleaning fresh water bodies contaminated with ionic forms of heavy metals.

A Survey of the Invasive Aquatic and Riparian Plants of the Lower Rio Grande

National Research Council Canada - National Science Library

Owens, Chetta S; Grodowitz, Michael J; Nibling, Fred

2005-01-01

.... In 2001 and 2003, surveys were conducted starting below Amistad Reservoir to immediately below Falcon Reservoir to assess the distribution and expansion of the hydrilla infestations and document...

A Survey of the Invasive Aquatic and Riparian Plants of the Low Rio Grande

National Research Council Canada - National Science Library

Owens, Chetta S; Grodowitz, Michael J; Nibling, Fred

2005-01-01

.... In 2001 and 2003, surveys were conducted starting below Amistad Reservoir to immediately below Falcon Reservoir to assess the distribution and expansion of the hydrilla infestations and document...

Effects of submergence on growth and survival of saplings of three wetland trees differing in adaptive mechanisms for flood tolerance

Directory of Open Access Journals (Sweden)

Fumiko Iwanaga

2015-04-01

Full Text Available Aim of study: Withstanding total submergence and reaeration following submergence is essential for the survival and establishment of wetland species. We focused on “LOES–low oxygen escape syndrome” and “LOQS–low oxygen quiescence syndrome” and compared tolerances to total submergence among wetland woody species differing in morphological adaptation to soil flooding. Area of study, materials and methods: This study examined the survival of 2-year-old saplings of Taxodium distichum and Metasequioia glyptostroboides (LOQS species, and Alnus japonica (LOES species, during and after total submergence. Saplings were completely submerged, then de-submerged to determine trends in survival and growth Main results: The M. glyptostroboides and A. japonica saplings could not survive prolonged submergence for more than 8 weeks, whereas saplings of T. distichum survived for over 2 years. Submerged saplings of all species showed no significant growth or modifications in morphology and anatomy under water, such as shoot elongation, adventitious root formation, and/or aerenchyma development. All T. distichum saplings that were de-submerged in the second year had the same pattern of shoot growth regardless of differences in timing and seasonality of de-submergence. Wood formation in T. distichum saplings ceased during submergence and resumed after de-submergence in spring and summer, but not in autumn. Research highlights: T. distichum saplings, which survived longer submergence periods than A. japonica and M. glyptostroboides, had physiological characteristics, such as suspension of growth and metabolism, which allowed survival of protracted total submergence (at least 2 years when saplings were immersed during the dormant stage before leaf flushing.

The sunflower transcription factor HaHB11 improves yield, biomass and tolerance to flooding in transgenic Arabidopsis plants.

Science.gov (United States)

Cabello, Julieta V; Giacomelli, Jorge I; Piattoni, Claudia V; Iglesias, Alberto A; Chan, Raquel L

2016-03-20

HaHB11 is a member of the sunflower homeodomain-leucine zipper I subfamily of transcription factors. The analysis of a sunflower microarray hybridized with RNA from HaHB11-transformed leaf-disks indicated the regulation of many genes encoding enzymes from glycolisis and fermentative pathways. A 1300bp promoter sequence, fused to the GUS reporter gene, was used to transform Arabidopsis plants showing an induction of expression after flooding treatments, concurrently with HaHB11 regulation by submergence in sunflower. Arabidopsis transgenic plants expressing HaHB11 under the control of the CaMV 35S promoter and its own promoter were obtained and these plants exhibited significant increases in rosette and stem biomass. All the lines produced more seeds than controls and particularly, those of high expression level doubled seeds yield. Transgenic plants also showed tolerance to flooding stress, both to submergence and waterlogging. Carbohydrates contents were higher in the transgenics compared to wild type and decreased less after submergence treatments. Finally, transcript levels of selected genes involved in glycolisis and fermentative pathways as well as the corresponding enzymatic activities were assessed both, in sunflower and transgenic Arabidopsis plants, before and after submergence. Altogether, the present work leads us to propose HaHB11 as a biotechnological tool to improve crops yield, biomass and flooding tolerance. Copyright © 2016 Elsevier B.V. All rights reserved.

Waste Treatment and Immobilization Plant U. S. Department of Energy Office of River Protection Submerged Bed Scrubber Condensate Disposition Project - 13460

Energy Technology Data Exchange (ETDEWEB)

Yanochko, Ronald M. [Washington River Protection Solutions, P.O. Box 850, Richland, Washington 99352 (United States); Corcoran, Connie [AEM Consulting, LLC, 1201 Jadwin Avenue, Richland, Washington 99352 (United States)

2013-07-01

The Hanford Waste Treatment and Immobilization Plant (WTP) will generate an off-gas treatment system secondary liquid waste stream [submerged bed scrubber (SBS) condensate], which is currently planned for recycle back to the WTP Low Activity Waste (LAW) melter. This SBS condensate waste stream is high in Tc-99, which is not efficiently captured in the vitrified glass matrix [1]. A pre-conceptual engineering study was prepared in fiscal year 2012 to evaluate alternate flow paths for melter off-gas secondary liquid waste generated by the WTP LAW facility [2]. This study evaluated alternatives for direct off-site disposal of this SBS without pre-treatment, which mitigates potential issues associated with recycling. This study [2] concluded that SBS direct disposal is a viable option to the WTP baseline. The results show: - Off-site transportation and disposal of the SBS condensate is achievable and cost effective. - Reduction of approximately 4,325 vitrified WTP Low Activity Waste canisters could be realized. - Positive WTP operational impacts; minimal WTP construction impacts are realized. - Reduction of mass flow from the LAW Facility to the Pretreatment Facility by 66%. - Improved Double Shell Tank (DST) space management is a benefit. (authors)

A Survey of the Invasive Aquatic and Riparian Plants of the Lower Rio Grande, 2004

National Research Council Canada - National Science Library

Owens, Chetta S; Grodowitz, Michael J; Nibling, Fred

2005-01-01

.... In 2004, surveys were conducted starting below Amistad Reservoir to immediately below Falcon Reservoir to assess the distribution and expansion of hydrilla infestations and document the presence...

The effect of submergence on structural response in confined pools

International Nuclear Information System (INIS)

Sturm, A.J. Jr.; Song, C.C.S.

1980-01-01

In this paper the response of single and multi degree of submerged systems is investigated. The complete equations of motions including fluid coupling terms are developed for submerged bodies where the surrounding fluid is both moving in phase and out of phase with the support motion. The analysis considers both structural and fluid damping. Also included is an analysis of two degrees of freedom fluid coupling for submerged bodies completely enclosed within another body. In this case limiting conditions of the inner body hydrodynamic mass are examined, along the frequency response characteristics of these systems. The paper developes a simplified forcing function approach for in phase fluid support motion systems. This method is applicable for both modal-spectral and time history dynamic analyses of any linear structure. The results of the analysis are expanded for s structures with non-linear support configuration, i.e. (sliding or rocking bases) to again define a simplified analytical approach accounting for in phase fluid support motion. (orig.)

Suspension of Egg Hatching Caused by High Humidity and Submergence in Spider Mites.

Science.gov (United States)

Ubara, Masashi; Osakabe, Masahiro

2015-08-01

We tested the effects of high humidity and submergence on egg hatching of spider mites. In both the high humidity and submergence treatments, many Tetranychus and Panonychus eggs did not hatch until after the hatching peak of the lower humidity or unsubmerged controls. However, after humidity decreased or water was drained, many eggs hatched within 1-3 h. This was observed regardless of when high humidity or submergence treatments were implemented: either immediately after oviposition or immediately before hatching was due. Normal eyespot formation was observed in most eggs in the high humidity and submergence treatments, which indicates that spider mite embryos develop even when eggs are underwater. Therefore, delays in hatching are not caused by delayed embryonic development. A delay in hatching was always observed in Panonychus citri (McGregor) but was more variable in Tetranychus urticae Koch and Tetranychus kanzawai Kishida. The high humidity and submergence treatments affected but did not suppress larval development in these species. In contrast, many Oligonychus eggs died following the high humidity treatments. In Tetranychus and Panonychus spider mites, suspension of egg hatching may mitigate the adverse effects of rainfall. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Invasive crayfish threaten the development of submerged macrophytes in lake restoration.

Science.gov (United States)

van der Wal, Jessica E M; Dorenbosch, Martijn; Immers, Anne K; Vidal Forteza, Constanza; Geurts, Jeroen J M; Peeters, Edwin T H M; Koese, Bram; Bakker, Elisabeth S

2013-01-01

Submerged macrophytes enhance water transparency and aquatic biodiversity in shallow water ecosystems. Therefore, the return of submerged macrophytes is the target of many lake restoration projects. However, at present, north-western European aquatic ecosystems are increasingly invaded by omnivorous exotic crayfish. We hypothesize that invasive crayfish pose a novel constraint on the regeneration of submerged macrophytes in restored lakes and may jeopardize restoration efforts. We experimentally investigated whether the invasive crayfish (Procambarus clarkii Girard) affects submerged macrophyte development in a Dutch peat lake where these crayfish are expanding rapidly. Seemingly favourable abiotic conditions for macrophyte growth existed in two 0.5 ha lake enclosures, which provided shelter and reduced turbidity, and in one lake enclosure iron was added to reduce internal nutrient loading, but macrophytes did not emerge. We transplanted three submerged macrophyte species in a full factorial exclosure experiment, where we separated the effect of crayfish from large vertebrates using different mesh sizes combined with a caging treatment stocked with crayfish only. The three transplanted macrophytes grew rapidly when protected from grazing in both lake enclosures, demonstrating that abiotic conditions for growth were suitable. Crayfish strongly reduced biomass and survival of all three macrophyte species while waterfowl and fish had no additive effects. Gut contents showed that crayfish were mostly carnivorous, but also consumed macrophytes. We show that P. clarkii strongly inhibit macrophyte development once favourable abiotic conditions for macrophyte growth are restored. Therefore, expansion of invasive crayfish poses a novel threat to the restoration of shallow water bodies in north-western Europe. Prevention of introduction and spread of crayfish is urgent, as management of invasive crayfish populations is very difficult.

Effects of stern-foil submerged elevation on the lift and drag of a hydrofoil craft

Science.gov (United States)

Suastika, K.; Apriansyah

2018-03-01

Effects of the stern-foil submerged elevation on the lift and drag of a hydrofoil craft are studied by using computational fluid dynamics (CFD) and by considering three alternative stern-foil submerged elevations. The submerged elevation of the front foil is kept constant in all the alternatives. From among the alternatives, the deepest stern-foil placement results in the highest stern-foil lift with the highest foil’s lift-to-drag ratio. However, considering the lift-to-drag ratio of the whole foil-strut-hull system, the shallowest stern-foil placement results in the highest lift-to-drag ratio. The struts and the foil’s submerged elevation significantly affects the drag of the whole foil-strut-hull system.

Measurement of Submerged Oil/Gas Leaks using ROV Video

Science.gov (United States)

Shaffer, Franklin; de Vera, Giorgio; Lee, Kenneth; Savas, Ömer

2013-11-01

Drilling for oil or gas in the Gulf of Mexico is increasing rapidly at depths up to three miles. The National Commission on the Deepwater Horizon Oil Leak concluded that inaccurate estimates of the leak rate from the Deepwater Horizon caused an inadequate response and attempts to cap the leak to fail. The first response to a submerged oil/gas leak will be to send a Remotely Operated Vehicle (ROV) down to view the leak. During the response to the Deepwater Horizon crisis, the authors Savas and Shaffer were members of the Flow Rate Technical Group's Plume Team who used ROV video to develop the FRTG's first official estimates of the oil leak rate. Savas and Shaffer developed an approach using the larger, faster jet features (e.g., turbulent eddies, vortices, entrained particles) in the near-field developing zone to measure discharge rates. The authors have since used the Berkeley Tow Tank to test this approach on submerged dye-colored water jets and compressed air jets. Image Correlation Velocimetry has been applied to measure the velocity of visible features. Results from tests in the Berkeley Tow Tank and submerged oil jets in the OHMSETT facility will be presented.

Detecting submerged features in water: modeling, sensors, and measurements

Science.gov (United States)

Bostater, Charles R., Jr.; Bassetti, Luce

2004-11-01

It is becoming more important to understand the remote sensing systems and associated autonomous or semi-autonomous methodologies (robotic & mechatronics) that may be utilized in freshwater and marine aquatic environments. This need comes from several issues related not only to advances in our scientific understanding and technological capabilities, but also from the desire to insure that the risk associated with UXO (unexploded ordnance), related submerged mines, as well as submerged targets (such as submerged aquatic vegetation) and debris left from previous human activities are remotely sensed and identified followed by reduced risks through detection and removal. This paper will describe (a) remote sensing systems, (b) platforms (fixed and mobile, as well as to demonstrate (c) the value of thinking in terms of scalability as well as modularity in the design and application of new systems now being constructed within our laboratory and other laboratories, as well as future systems. New remote sensing systems - moving or fixed sensing systems, as well as autonomous or semi-autonomous robotic and mechatronic systems will be essential to secure domestic preparedness for humanitarian reasons. These remote sensing systems hold tremendous value, if thoughtfully designed for other applications which include environmental monitoring in ambient environments.

Submerged macrophytes modify bacterial community composition in sediments in a large, shallow, freshwater lake.

Science.gov (United States)

Zhao, Da-Yong; Liu, Peng; Fang, Chao; Sun, Yi-Meng; Zeng, Jin; Wang, Jian-Qun; Ma, Ting; Xiao, Yi-Hong; Wu, Qinglong L

2013-04-01

Submerged aquatic macrophytes are an important part of the lacustrine ecosystem. In this study, the bacterial community compositions in the rhizosphere sediments from three kinds of submerged macrophytes (Ceratophyllum demersum, Potamogeton crispus, and Vallisneria natans) were investigated to determine whether submerged macrophytes could drive the variation of bacterial community in the eutrophic Taihu Lake, China. Molecular techniques, including terminal restriction fragment length polymorphism (T-RFLP) of PCR-amplified 16S rRNA gene and clone libraries, were employed to analyze the bacterial community compositions. Remarkable differences of the T-RFLP patterns were observed among the different samples, and the results of LIBSHUFF analysis also confirmed that the bacterial community compositions in the rhizosphere sediments of three kinds of submerged macrophytes were statistically different from that of the unvegetated sediment. Acidobacteria, Deltaproteobacteria, and Betaproteobacteria were the dominant bacterial groups in the rhizosphere sediments of Ceratophyllum demersum, Potamogeton crispus, and Vallisneria natans, respectively, accounting for 15.38%, 29.03%, and 18.00% of the total bacterial abundances. Our study demonstrated that submerged macrophytes could influence the bacterial community compositions in their rhizosphere sediments, suggesting that macrophytes have an effect on the cycling and transportation of nutrients in the freshwater lake ecosystem.

Effective mass and damping of submerged structures

International Nuclear Information System (INIS)

Dong, R.G.

1979-01-01

A number of structures important for safety in nuclear power plants are submerged in water. These include spent fuel storage racks, main pressure relief valve lines, and internal structures in the reactor vessel. Dynamic analyses of such structures must include the force and damping effects of water. A wide variety of modeling assumptions are being used in design analyses, and currently there are no uniform positions by which to judge the adequacy of the assumptions . A study was caried out to establish a technical basis for evaluating the assymptions and to recommend suitable methods to describe the effects of the water. The results of the study were based on information published in the literature or conveyed by industrial firms. A survey of 32 firms and 49 technical references was carried out. Heavy emphasis was placed on validating the results with available experimental data. The information collected apply generally to idealized structures such as single isolated members, arrays of members and coaxial cylinders. The results of the study are categorized with respect to such idealized structures, and the applicability to actual reactor structures was discussed through observations and recommendations. (orig.)

Submerged reef systems on the central western continental shelf of India

Digital Repository Service at National Institute of Oceanography (India)

Vora, K.H.; Almeida, F.

-262 255 Elsevier Science Publishers B.V., Amsterdam -- Printed in the Netherlands Letter Section Submerged Reef Systems on the Central Western Continental Shelf of India K.H. VORA and F. ALMEIDA National Institute of Oceanography, Dona Paula, Goa 403... 004 (India) (Revision accepted October 26, 1989) Abstract Vora, K.H. and Almeida, F., 1990. Submerged reef systems on the central western continental shelf of India. Mar. Geol., 91: 255-262. Echosounding and sidescan sonar data from the western...

Durability performance of submerged concrete structures - phase 2.

Science.gov (United States)

2015-09-01

This project determined that severe corrosion of steel can occur in the submerged : portions of reinforced concrete structures in marine environments. Field studies of decommissioned : pilings from Florida bridges revealed multiple instances of stron...

[Radioecological monitoring of the Yenisei River and citological characterization of a submerged aquatic plant Elodea canadensis].

Science.gov (United States)

Bolsunovskiĭ, A Ia; Muratova, E N; Sukovatyĭ, A G; Pimenov, A V; Sanzharaeva, E A; Zotina, T A; Sedel'nikova, T S; Pan'kov, E V; Kornilova, M G

2007-01-01

The study was devoted to investigation of the contents of radionuclides and of heavy metals and to evaluate the frequency of chromosomal aberrations in samples of Elodea canadensis, a submerged plant, collected in different parts of the Yenisei River. The samples were collected in the area subjected to radioactive impact of the Mining-and-Chemical Combine (MCC) at Zheleznogorsk and in the control area, upstream of the MCC. The investigations shown that elodea biomass in the area affected by MCC operation contained a long inventory of artificial radionuclides typical for the MCC discharges. The upstream of the MCC, in the control sampling area, the sediments and the elodea biomass contained only one artificial radionuclide--137Cs. Thus, the exposure doses to elodea shoots and roots upstream of the MCC are small (not more than 8 microGy/d) and the main contribution info the dose is made by natural radionuclides. At the MCC discharge site (the village of Atamanovo) and at the downstream of it, the total dose rate increases almost an order of magnitude, reaching its maximal values--72 microGy/d for elodea shoots and 58 microGy/d for its roots. Cytogenetic investigations of elodea roots shown that at the MCC discharge site (the village of Atamanovo) and at downstream of it the occurrence of chromosomal aberrations in ana-telophase and in metaphase cells of elodea was considerably higher than in the control area. It is highly probable that this simultaneous dramatic increase in the total exposure rate and the occurrence of chromosomal aberrations in elodea is associated with the radiation factor. It is suggested that elodea is affected not only by the radiation factor but also by the chemical factor--toxicity of heavy metals.

Response of Submerged Macrophyte Communities to External and Internal Restoration Measures in North Temperate Shallow Lakes

Science.gov (United States)

Hilt, Sabine; Alirangues Nuñez, Marta M.; Bakker, Elisabeth S.; Blindow, Irmgard; Davidson, Thomas A.; Gillefalk, Mikael; Hansson, Lars-Anders; Janse, Jan H.; Janssen, Annette B. G.; Jeppesen, Erik; Kabus, Timm; Kelly, Andrea; Köhler, Jan; Lauridsen, Torben L.; Mooij, Wolf M.; Noordhuis, Ruurd; Phillips, Geoff; Rücker, Jacqueline; Schuster, Hans-Heinrich; Søndergaard, Martin; Teurlincx, Sven; van de Weyer, Klaus; van Donk, Ellen; Waterstraat, Arno; Willby, Nigel; Sayer, Carl D.

2018-01-01

Submerged macrophytes play a key role in north temperate shallow lakes by stabilizing clear-water conditions. Eutrophication has resulted in macrophyte loss and shifts to turbid conditions in many lakes. Considerable efforts have been devoted to shallow lake restoration in many countries, but long-term success depends on a stable recovery of submerged macrophytes. However, recovery patterns vary widely and remain to be fully understood. We hypothesize that reduced external nutrient loading leads to an intermediate recovery state with clear spring and turbid summer conditions similar to the pattern described for eutrophication. In contrast, lake internal restoration measures can result in transient clear-water conditions both in spring and summer and reversals to turbid conditions. Furthermore, we hypothesize that these contrasting restoration measures result in different macrophyte species composition, with added implications for seasonal dynamics due to differences in plant traits. To test these hypotheses, we analyzed data on water quality and submerged macrophytes from 49 north temperate shallow lakes that were in a turbid state and subjected to restoration measures. To study the dynamics of macrophytes during nutrient load reduction, we adapted the ecosystem model PCLake. Our survey and model simulations revealed the existence of an intermediate recovery state upon reduced external nutrient loading, characterized by spring clear-water phases and turbid summers, whereas internal lake restoration measures often resulted in clear-water conditions in spring and summer with returns to turbid conditions after some years. External and internal lake restoration measures resulted in different macrophyte communities. The intermediate recovery state following reduced nutrient loading is characterized by a few macrophyte species (mainly pondweeds) that can resist wave action allowing survival in shallow areas, germinate early in spring, have energy-rich vegetative

Response of Submerged Macrophyte Communities to External and Internal Restoration Measures in North Temperate Shallow Lakes.

Science.gov (United States)

Hilt, Sabine; Alirangues Nuñez, Marta M; Bakker, Elisabeth S; Blindow, Irmgard; Davidson, Thomas A; Gillefalk, Mikael; Hansson, Lars-Anders; Janse, Jan H; Janssen, Annette B G; Jeppesen, Erik; Kabus, Timm; Kelly, Andrea; Köhler, Jan; Lauridsen, Torben L; Mooij, Wolf M; Noordhuis, Ruurd; Phillips, Geoff; Rücker, Jacqueline; Schuster, Hans-Heinrich; Søndergaard, Martin; Teurlincx, Sven; van de Weyer, Klaus; van Donk, Ellen; Waterstraat, Arno; Willby, Nigel; Sayer, Carl D

2018-01-01

Submerged macrophytes play a key role in north temperate shallow lakes by stabilizing clear-water conditions. Eutrophication has resulted in macrophyte loss and shifts to turbid conditions in many lakes. Considerable efforts have been devoted to shallow lake restoration in many countries, but long-term success depends on a stable recovery of submerged macrophytes. However, recovery patterns vary widely and remain to be fully understood. We hypothesize that reduced external nutrient loading leads to an intermediate recovery state with clear spring and turbid summer conditions similar to the pattern described for eutrophication. In contrast, lake internal restoration measures can result in transient clear-water conditions both in spring and summer and reversals to turbid conditions. Furthermore, we hypothesize that these contrasting restoration measures result in different macrophyte species composition, with added implications for seasonal dynamics due to differences in plant traits. To test these hypotheses, we analyzed data on water quality and submerged macrophytes from 49 north temperate shallow lakes that were in a turbid state and subjected to restoration measures. To study the dynamics of macrophytes during nutrient load reduction, we adapted the ecosystem model PCLake. Our survey and model simulations revealed the existence of an intermediate recovery state upon reduced external nutrient loading, characterized by spring clear-water phases and turbid summers, whereas internal lake restoration measures often resulted in clear-water conditions in spring and summer with returns to turbid conditions after some years. External and internal lake restoration measures resulted in different macrophyte communities. The intermediate recovery state following reduced nutrient loading is characterized by a few macrophyte species (mainly pondweeds) that can resist wave action allowing survival in shallow areas, germinate early in spring, have energy-rich vegetative

Submerged beachrock preservation in the context of wave ravinement

Science.gov (United States)

Pretorius, Lauren; Green, Andrew N.; Andrew Cooper, J.

2018-02-01

This study examines a Holocene-aged submerged shoreline, Limestone Reef, located in the shallow subtidal zone of South Africa's east coast. It comprises an elongate, coast-oblique, slab-like outcrop of beachrock situated above the contemporary fair-weather wave base. It is currently undergoing mechanical disintegration. Its unique and rare preservation in a high-energy setting affords an opportunity to examine the mechanical processes occurring during wave ravinement associated with rising sea level. The submerged shoreline and the adjacent shoreface were examined using high-resolution seismic reflection, side-scan sonar and shallow-water multibeam echosounding techniques. Limestone Reef rests on top of unconsolidated Holocene deposits. The structure's surface is characterised by reef-perpendicular gullies with rubble derived from the slab fringing its seaward edge. Limestone Reef slopes gently seawards and has a steep landward-facing edge where gullies are most prominently developed. Teardrop-shaped rippled scour depressions, marked by high backscatter, are located seawards of the submerged shoreline. These elongate in a seaward direction and are filled with bioclastic gravels and residual rubble from Limestone Reef. The gullies in the upstanding structure are indicative of wave plucking and abrasion of the shoreline. The material exposed by the rippled scour depressions is identical to that comprising the postglacial ravinement surface identified in the offshore stratigraphy. These deposits are considered to represent the contemporary, actively forming wave ravinement surface. The results suggest that wave ravinement of submerged shorelines is a discontinuous process dominated by the seaward entrainment of material from its landward edge controlled by high-energy drawback during storm surges. The ravinement process appears to operate at the seasonal scale and averages out over the long-term millennial scale for the continuous surface.

Experimental motion behavior of submerged fuel racks

International Nuclear Information System (INIS)

Ellingson, F.J.; Wachter, W.; Moscardini, R.L.

1989-01-01

The design of submerged nuclear storage racks for light water reactor nuclear fuel has undergone a change from fixed position to a free-standing arrangement. Seismic analysis of the motion of the free-standing racks requires three-dimensional computer modeling that uses past studies of hydrodynamic mass and hydraulic coupling for rigid flat plates. This paper describes the results of experiments that show a reduced value for hydrodynamic mass and coupling forces when flexible elements are involved. To support this work, experiments were run with two full-scale welded box sections submerged in a water tank. The preliminary results indicate reduction in hydrodynamic mass due to box wall flexibility, a lack of impacting of box wall to box wall over the entire frequency range, and large hydrodynamic coupling forces under all test conditions. It is hypothesized that the coupling forces are sufficiently strong to prevent rotational motion of one rack when surrounded by adjacent racks

Measuring landscape-scale spread and persistence of an invaded submerged plant community from airborne remote sensing.

Science.gov (United States)

Santos, Maria J; Khanna, Shruti; Hestir, Erin L; Greenberg, Jonathan A; Ustin, Susan L

2016-09-01

Processes of spread and patterns of persistence of invasive species affect species and communities in the new environment. Predicting future rates of spread is of great interest for timely management decisions, but this depends on models that rely on understanding the processes of invasion and historic observations of spread and persistence. Unfortunately, the rates of spread and patterns of persistence are difficult to model or directly observe, especially when multiple rates of spread and diverse persistence patterns may be co-occurring over the geographic distribution of the invaded ecosystem. Remote sensing systematically acquires data over large areas at fine spatial and spectral resolutions over multiple time periods that can be used to quantify spread processes and persistence patterns. We used airborne imaging spectroscopy data acquired once a year for 5 years from 2004 to 2008 to map an invaded submerged aquatic vegetation (SAV) community across 2220 km 2 of waterways in the Sacramento-San Joaquin River Delta, California, USA, and measured its spread rate and its persistence. Submerged aquatic vegetation covered 13-23 km 2 of the waterways (6-11%) every year. Yearly new growth accounted for 40-60% of the SAV area, ~50% of which survived to following year. Spread rates were overall negative and persistence decreased with time. From this dataset, we were able to identify both radial and saltatorial spread of the invaded SAV in the entire extent of the Delta over time. With both decreasing spread rate and persistence, it is possible that over time the invasion of this SAV community could decrease its ecological impact. A landscape-scale approach allows measurements of all invasion fronts and the spatial anisotropies associated with spread processes and persistence patterns, without spatial interpolation, at locations both proximate and distant to the focus of invasion at multiple points in time. © 2016 by the Ecological Society of America.

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

Science.gov (United States)

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.

Elaboración de abono orgánico a partir de plantas acuáticas: Elodea (Hydrilla verticillata) y Jacinto o Lirio de agua (Eichhornia crassipes), procedentes del Lago de Coatepeque y Lago de Güija

OpenAIRE

Reyes de Cabrales, Cecilia Elizabeth

2009-01-01

El presente estudio tiene por finalidad elaborar un abono orgánico bajo la técnica de compostaje, conocida como proceso de descomposición aeróbica. Se realizaron tres formulaciones de abono a partir de las plantas acuáticas Elodea (Hydrilla verticillata) y Jacinto de agua (Eichhornia crassipes) en las siguientes proporciones: Elodea 100%, Jacinto de agua 100% y mezcla de ambas en una proporción de 50:50. A los abonos obtenidos se les realizaron análisis químico con la finalidad de cuantificar...

Competition for light and nutrients in layered communities of aquatic plants

NARCIS (Netherlands)

Van Gerven, Luuk P.A.; de Klein, J.J.M; Gerla, Daan J.; Kooi, B.W.; Kuiper, Jan J.; Mooij, Wolf M.

2015-01-01

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

Competition for Light and Nutrients in Layered Communities of Aquatic Plants

NARCIS (Netherlands)

van Gerven, L.P.A.; de Klein, J.J.M.; Gerla, D.J.; Kooi, B.W.; Kuiper, J.J.; Mooij, W.M.

2015-01-01

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

Competition for light and nutrients in layered communities of aquatic plants

NARCIS (Netherlands)

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

2015-01-01

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

Submerged AUV Charging Station

Science.gov (United States)

Jones, Jack A.; Chao, Yi; Curtin, Thomas

2014-01-01

Autonomous Underwater Vehicles (AUVs) are becoming increasingly important for military surveillance and mine detection. Most AUVs are battery powered and have limited lifetimes of a few days to a few weeks. This greatly limits the distance that AUVs can travel underwater. Using a series of submerged AUV charging stations, AUVs could travel a limited distance to the next charging station, recharge its batteries, and continue to the next charging station, thus traveling great distances in a relatively short time, similar to the Old West “Pony Express.” One solution is to use temperature differences at various depths in the ocean to produce electricity, which is then stored in a submerged battery. It is preferred to have the upper buoy submerged a reasonable distance below the surface, so as not to be seen from above and not to be inadvertently destroyed by storms or ocean going vessels. In a previous invention, a phase change material (PCM) is melted (expanded) at warm temperatures, for example, 15 °C, and frozen (contracted) at cooler temperatures, for example, 8 °C. Tubes containing the PCM, which could be paraffin such as pentadecane, would be inserted into a container filled with hydraulic oil. When the PCM is melted (expanded), it pushes the oil out into a container that is pressurized to about 3,000 psi (approx equals 20.7 MPa). When a valve is opened, the high-pressure oil passes through a hydraulic motor, which turns a generator and charges a battery. The low-pressure oil is finally reabsorbed into the PCM canister when the PCM tubes are frozen (contracted). Some of the electricity produced could be used to control an external bladder or a motor to the tether line, such that depth cycling is continued for a very long period of time. Alternatively, after the electricity is generated by the hydraulic motor, the exiting low-pressure oil from the hydraulic motor could be vented directly to an external bladder on the AUV, such that filling of the bladder

Crestal bone loss around submerged and nonsubmerged dental implants: A systematic review.

Science.gov (United States)

Al Amri, Mohammad D

2016-05-01

To my knowledge, there is no systematic review of crestal bone loss (CBL) around submerged and nonsubmerged dental implants. The purpose of this review was to systematically assess CBL around submerged and nonsubmerged dental implants. The addressed focused question was, "Does crestal and subcrestal placement of dental implants influence crestal bone levels?" Databases were searched from 1986 through October 2015 using different combinations of the following keywords: crestal, sub-crestal, bone loss, dental implant, submerged, and nonsubmerged. Reference lists of potentially relevant original and review articles were hand-searched to identify any further studies. Letters to the editor, case reports, commentaries, studies on platform-switched implants, and studies published in languages other than English were excluded. In total, 13 studies (6 human and 7 animal), which were performed at universities, were included. In the human studies, the number of participants ranged from 8 to 84 individuals. The follow-up period ranged from 1 to 5 years. CBL at the test sites ranged from 0.17 mm to 0.9 mm and at control sites from 0.02 mm to 1.4 mm. Five human studies reported no significant difference in CBL around implants placed at the test and control sites. All animal studies were performed in dogs with a mean age ranging from 1 to approximately 2 years. The follow-up period ranged from 2 to 6 months. Four animal studies reported no significant difference in CBL around submerged and nonsubmerged implants. No significant difference in CBL was found around submerged and nonsubmerged dental implants. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Production of extracellular aspartic protease in submerged ...

African Journals Online (AJOL)

Fungal milk-clotting enzymes have gained value as bovine Chymosin substitutes in the cheese industry. In this work, the effects of culture conditions on the production of extracellular milk clotting enzymes from Mucor mucedo DSM 809 in submerged fermentation were studied. The maximum activity was observed after 48 h ...

Submerged karst landforms observed by multibeam bathymetric survey in Nagura Bay, Ishigaki Island, southwestern Japan

Science.gov (United States)

Kan, Hironobu; Urata, Kensaku; Nagao, Masayuki; Hori, Nobuyuki; Fujita, Kazuhiko; Yokoyama, Yusuke; Nakashima, Yosuke; Ohashi, Tomoya; Goto, Kazuhisa; Suzuki, Atsushi

2015-01-01

Submerged tropical karst features were discovered in Nagura Bay on Ishigaki Island in the southern Ryukyu Islands, Japan. The coastal seafloor at depths shallower than ~ 130 m has been subjected to repeated and alternating subaerial erosion and sedimentation during periods of Quaternary sea-level lowstands. We conducted a broadband multibeam survey in the central area of Nagura Bay (1.85 × 2.7 km) and visualized the high-resolution bathymetric results over a depth range of 1.6-58.5 m. Various types of humid tropical karst landforms were found to coexist within the bay, including fluviokarst, doline karst, cockpit karst, polygonal karst, uvalas, and mega-dolines. Although these submerged karst landforms are covered by thick postglacial reef and reef sediments, their shapes and sizes are distinct from those associated with coral reef geomorphology. The submerged landscape of Nagura Bay likely formed during multiple glacial and interglacial periods. According to our bathymetric results and the aerial photographs of the coastal area, this submerged karst landscape appears to have developed throughout Nagura Bay (i.e., over an area of approximately 6 × 5 km) and represents the largest submerged karst in Japan.

The Geology of Burma (Myanmar): An Annotated Bibliography of Burma’s Geology, Geography and Earth Science

Science.gov (United States)

2008-09-01

Eichornia-Crassipes; Ephydatia-Fluviatilis; Hydrilla; Imperata ; Inle; Intha; Shan; Utricularia. Abstract: cultural data on the people and a bibliography...characterized by dipterocarpus Bibliography of Burman Earth Science September 2008 71 tuberculatus and associated plants; the other by imperata . The

Experimental investigation of submerged single jet impingement using Cu–water nanofluid

International Nuclear Information System (INIS)

Li Qiang; Xuan Yimin; Yu Feng

2012-01-01

Jet impingement cooling is a vital technique for thermal management of electronic devices of high-heat-flux by impinging fluid on a heater surface due to its high local heat transfer rates. In this paper, two types of Cu–water nanofluids (Cu particles with 25 nm diameter or 100 nm) are introduced into submerged single jet impingement cooling system as the working fluid. The heat transfer features of the nanofluids were experimentally investigated. The effects of the nanoparticle concentration, Reynolds number, nozzle-to-plate distance, fluid temperature, and nanoparticle diameter on the heat transfer performances of the jet impingement of nanofluids are discussed. The experimental results show that the suspended nanoparticles remarkably increase the convective heat transfer coefficient of the base fluid. The convective heat transfer coefficient of Cu–water nanofluid with the volume fraction of 3.0% has 52% higher than the pure water. The experiments also revealed that the suspended nanoparticles brought almost no extra addition of pressure drop in both submerged single jet impingement. In addition, by considering the effects of the suspended nanoparticles as well as the condition of impinging jet, a new heat transfer correlation of nanofluids for the submerged single jet impingement has been proposed. - Highlights: ► Cu–water nanofluids are introduced into submerged single jet impingement. ► The affecting parameters on the heat transfer performances of nanofluids are discussed. ► New heat transfer correlation of nanofluid for single jet impingement is proposed.

Production of Alpha Amylase by Bacillus cereus in Submerged Fermentation

Directory of Open Access Journals (Sweden)

Helen H. Raplong

2014-09-01

Full Text Available Microorganisms have the ability to secrete enzymes when they are grown in the presence of certain substrates. Amylases are among the most important industrial enzymes and are of great significance in biotechnological studies. Bacteria belonging to the genus Bacillus were isolated using mannitol egg yolk polymyxin B (MYP agar a highly selective media for Bacillus cereus isolation. The isolates were tested for α-amylase production on nutrient agar supplemented with starch and in submerged fermentation. The bacteria isolated and identified (using the Microgen Bacillus identification kit were all Bacillus cereus and SB2 had the largest zone of hydrolysis of 12mm on nutrient agar supplemented with starch as well as the highest enzyme activity of 1.62U/ml. Amylase activity of 2.56U/ml was obtained after 24 hours incubation in submerged fermentation. When amylase enzyme production parameters where optimized, maximum amylase activity was obtained at a pH of 6.5, temperature of 350C, incubation time of 24 hours and 4% inoculums concentration. Bacillus cereus SB2 is a potential isolate for alpha-amylase production with soluble starch as the sole carbon source in submerged fermentation.

Vibration analysis of partially cracked plate submerged in fluid

Science.gov (United States)

Soni, Shashank; Jain, N. K.; Joshi, P. V.

2018-01-01

The present work proposes an analytical model for vibration analysis of partially cracked rectangular plates coupled with fluid medium. The governing equation of motion for the isotropic plate based on the classical plate theory is modified to accommodate a part through continuous line crack according to simplified line spring model. The influence of surrounding fluid medium is incorporated in the governing equation in the form of inertia effects based on velocity potential function and Bernoulli's equations. Both partially and totally submerged plate configurations are considered. The governing equation also considers the in-plane stretching due to lateral deflection in the form of in-plane forces which introduces geometric non-linearity into the system. The fundamental frequencies are evaluated by expressing the lateral deflection in terms of modal functions. The assessment of the present results is carried out for intact submerged plate as to the best of the author's knowledge the literature lacks in analytical results for submerged cracked plates. New results for fundamental frequencies are presented as affected by crack length, fluid level, fluid density and immersed depth of plate. By employing the method of multiple scales, the frequency response and peak amplitude of the cracked structure is analyzed. The non-linear frequency response curves show the phenomenon of bending hardening or softening and the effect of fluid dynamic pressure on the response of the cracked plate.

Benthic bacterial diversity in submerged sinkhole ecosystems.

Science.gov (United States)

Nold, Stephen C; Pangborn, Joseph B; Zajack, Heidi A; Kendall, Scott T; Rediske, Richard R; Biddanda, Bopaiah A

2010-01-01

Physicochemical characterization, automated ribosomal intergenic spacer analysis (ARISA) community profiling, and 16S rRNA gene sequencing approaches were used to study bacterial communities inhabiting submerged Lake Huron sinkholes inundated with hypoxic, sulfate-rich groundwater. Photosynthetic cyanobacterial mats on the sediment surface were dominated by Phormidium autumnale, while deeper, organically rich sediments contained diverse and active bacterial communities.

Contribution of seedling vigour and anoxia/hypoxia-responsive genes to submergence tolerance in Vietnamese lowland rice (Oryza sativa L.

Directory of Open Access Journals (Sweden)

Hien Thi Thu Vu

2016-09-01

Full Text Available A direct-seeded rice cultivation system has been widely adopted in Asian countries. Optimum germination and vigorous seedling growth under submergence are key traits for the practice of direct seeding. We studied the post-germination seedling vigour in Vietnamese lowland rice accessions based on three bio-parameters, shoot elongation growth under five-day submergence in water-filled test-tubes, seedling recovery rate five days after transferring submerged seedlings to pots with soil and seedling survival rate 21 days after sowing seeds in nursery beds and immediate incubation under submergence. A large diversity was found in seedling vigour thus estimated among the accessions. Significantly high correlations were observed among all three bio-parameters, verifying the contribution of seedling vigour to the manifestation of submergence tolerance at this critical stage of rice development. To examine the roles of anoxia/hypoxia-responsive genes, the expression of 17 candidate genes was studied by reverse transcription polymerase chain reaction (RT-PCR and compared between selected vigorous and non-vigorous groups of accessions. Transcripts of all but two genes showed marked accumulation in submerged seedlings. No differences, however, were found between the two contrasting groups. The observed common and coordinate expression of anoxia/hypoxia-induced genes suggests that they might assume roles in attaining baseline tolerance against submergence stress. It was also suggested that some unknown genetic factors are operating in determining cultivar/genotype-specific levels of submergence tolerance as assessed by post-germination seedling vigour.

Mixing Characteristics during Fuel Coolant Interaction under Reactor Submerged Conditions

International Nuclear Information System (INIS)

Hong, S. W.; Na, Y. S.; Hong, S. H.; Song, J. H.

2014-01-01

A molten material is injected into an interaction chamber by free gravitation fall. This type of fuel coolant interaction could happen to operating plants. However, the flooding of a reactor cavity is considered as SAM measures for new PWRs such as APR-1400 and AP1000 to assure the IVR of a core melt. In this case, a molten corium in a reactor is directly injected into water surrounding the reactor vessel without a free fall. KAERI has carried out fuel coolant interaction tests without a free fall using ZrO 2 and corium to simulate the reactor submerged conditions. There are four phases in a steam explosion. The first phase is a premixing phase. The premixing is described in the literature as follows: during penetration of melt into water, hydrodynamic instabilities, generated by the velocities and density differences as well as vapor production, induce fragmentation of the melt into particles; the particles fragment in turn into smaller particles until they reach a critical size such that the cohesive forces (surface tension) balance exactly the disruptive forces (inertial); and the molten core material temperature (>2500 K) is such that the mixing always occurs in the film boiling regime of the water: It is very important to qualify and quantify this phase because it gives the initial conditions for a steam explosion This paper mainly focuses on the observation of the premixing phase between a case with 1 m free fall and a case without a free fall to simulate submerged reactor condition. The premixing behavior between a 1m free fall case and reactor case submerged without a free fall is observed experimentally. The average velocity of the melt front passing through 1m water pool; - Case without a free fall: The average velocity of corium, 2.7m/s, is faster than ZrO 2 , 2.3m/s, in water. - Cases of with a 1 m free fall and without a free fall : The case without a free fall is about two times faster than a case with a 1 m free fall. Bubble characteristics; - Case

A model for the effect of submerged aquatic vegetation on turbulence induced by an oscillating grid

Science.gov (United States)

Pujol, Dolors; Colomer, Jordi; Serra, Teresa; Casamitjana, Xavier

2012-12-01

The aim of this study is to model, under controlled laboratory conditions, the effect of submerged aquatic vegetation (SAV) on turbulence generated in a water column by an oscillating grid turbulence (OGT). Velocity profiles have been measured by an acoustic Doppler velocimeter (MicroADV). Experimental conditions are analysed in two canopy models (rigid and semi-rigid), using nine plant-to-plant distances (ppd), three stem diameters (d), four types of natural SAV (Cladium mariscus, Potamogeton nodosus, Myriophyllum verticillatum and Ruppia maritima) and two oscillation grid frequencies (f). To quantify this response, we have developed a non-dimensional model, with a specific turbulent kinetic energy (TKE), f, stroke (s), d, ppd, distance from the virtual origin to the measurement (zm) and space between grid bars (M). The experimental data show that, at zm/zc 1, TKE decreases faster with zm and scales to the model variables according to TKE/(f·s)∝(·(. Therefore, at zm/zc > 1 the TKE is affected by the geometric characteristics of the plants (both diameter and plant-to-plant distance), an effect called sheltering. Results from semi-rigid canopies and natural SAV are found to scale with the non-dimensional model proposed for rigid canopies. We also discuss the practical implications for field conditions (wind and natural SAV).

Improvement of Xylanase Production by Cochliobolus sativus in Submerged Culture

Directory of Open Access Journals (Sweden)

Yasser Bakri

2008-01-01

Full Text Available The xylanase production by a new Cochliobolus sativus Cs5 strain was improved under submerged fermentation. The xylanase was induced by xylan and repressed by glucose, sucrose, maltose, xylose, starch and cellulose. Highest enzyme production (98.25 IU/mL was recorded when wheat straw (4 % by mass per volume was used as a carbon source after 120 h of incubation. NaNO3 increased xylanase production 5.4-fold as compared to the control. Optimum initial pH was found to be 4.5 to 5. The C. sativus Cs5 strain grown under submerged culture in a simple medium proved to be a promising microorganism for xylanase production.

Examination of two lowland rice cultivars reveals that gibberellin-dependent early response to submergence is not necessarily mediated by ethylene.

Science.gov (United States)

Dubois, Vincent; Moritz, Thomas; García-Martínez, José L

2011-01-01

Using two lowland rice (Oryza sativa L.) cultivars we found that in both cases submerged-induced elongation early after germination depends on gibberellins (GAs). Submergence increases the content of the active GA 1 by enhancing the expression of GA biosynthesis genes, thus facilitating the seedlings to escape from the water and preventing asphyxiation. However, the two cultivars differ in their response to ethylene. The cultivar Senia (short), by contrast to cultivar Bomba (tall), does not elongate after ethylene application, and submerged-induced elongation is not negated by an inhibitor of ethylene perception. Also, while ethylene emanation in Senia is not altered by submergence, Bomba seedlings emanate more ethylene upon de-submergence, associated with enhanced expression of the ethylene biosynthesis gene OsACS5. The cultivar Senia thus allows the possibility of clarifying the role of ethylene and other factors as triggers of GA biosynthesis enhancement in rice seedlings under submergence.

Production of ethanol from mesquite [Prosopis juliflora (SW) D.C.] pods mash by Zymomonas mobilis in submerged fermentation

Energy Technology Data Exchange (ETDEWEB)

Silva, Celiane Gomes Maia da [Universidade Federal Rural de Pernambuco (UFRPE), Recife, PE (Brazil). Dept. de Ciencias Domesticas; Andrade, Samara Alvachian Cardoso; Schuler, Alexandre Ricardo Pereira [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Engenharia Quimica; Souza, Evandro Leite de [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Dept. de Nutricao; Stamford, Tania Lucia Montenegro [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Nutricao], E-mail: tlmstamford@yahoo.com.br

2011-01-15

Mesquite [Prosopis juliflora (SW) D.C.], a perennial tropical plant commonly found in Brazilian semi-arid region, is a viable raw material for fermentative processes because of its low cost and production of pods with high content of hydrolyzable sugars which generate many compounds, including ethanol. This study aimed to evaluate the use of mesquite pods as substrate for ethanol production by Z. mobilis UFPEDA- 205 in a submerged fermentation. The fermentation was assessed for rate of substrate yield to ethanol, rate of ethanol production and efficiency of fermentation. The very close theoretical (170 g L{sup -1}) and experimental (165 g L{sup -1}) maximum ethanol yields were achieved at 36 h of fermentation. The highest counts of Z. mobilis UFEPEDA-205 (both close to 6 Log cfu mL{sup -1}) were also noted at 36 h. Highest rates of substrate yield to ethanol (0.44 g ethanol g glucose{sup -1}), of ethanol production (4.69 g L{sup -1} h{sup -1}) and of efficiency of fermentation (86.81%) were found after 30 h. These findings suggest mesquite pods as an interesting substrate for ethanol production using submerged fermentation by Z. mobilis. (author)

NRC Information No. 89-63: Possible submergence of electrical circuits located above the flood level because of water intrusion and lack of drainage

International Nuclear Information System (INIS)

Rossi, C.E.

1992-01-01

This information notice is being provided to alert addressees that electrical circuits located above the plant flood level within electrical enclosures may become submerged in water because appropriate drainage has not been provided. Failure of electrical circuits during service conditions, including postulated accidents, can occur due to submergence if water enters these enclosures and there is no provision for drainage. The electrical enclosures addressed by this notice include terminal boxes, junction boxes, pull boxes, conduits, Condulets, and other enclosures for end-use equipment (such as limit switches, motor operators, and electrical penetrations), the contents of which may include cables, terminal blocks, electrical splices and connectors. Information Notice 84-57, ''Operating Experience Related to Moisture Intrusion on Safety-Related Electrical Equipment at Commercial Power Plants,'' addressed watertight sealing of all electrical conduits to junction boxes and conduit-to-terminal box connection points for safety-related equipment located in areas of the reactor building as well as for areas that are potentially subject to high temperature steam or water impingement. This notice further addressed the importance of ensuring that box drain holes and equipment interfaces are in conformance with the test setup established during equipment qualification testing and with the vendor's recommendations

Investigation of a submerged membrane reactor for continuous biomass hydrolysis

Energy Technology Data Exchange (ETDEWEB)

Malmali, Mohammadmahdi; Stickel, Jonathan; Wickramasinghe, S. Ranil

2015-10-01

Enzymatic hydrolysis of cellulose is one of the most costly steps in the bioconversion of lignocellulosic biomass. Use of a submerged membrane reactor has been investigated for continuous enzymatic hydrolysis of cellulose thus allowing for greater use of the enzyme compared to a batch process. Moreover, the submerged 0.65 μm polyethersulfone microfiltration membrane avoids the need to pump a cellulose slurry through an external loop. Permeate containing glucose is withdrawn at pressures slightly below atmospheric pressure. The membrane rejects cellulose particles and cellulase enzyme bound to cellulose. Our proof-of-concept experiments have been conducted using a modified, commercially available membrane filtration cell under low fluxes around 75 L/(m2 h). The operating flux is determined by the rate of glucose production. Maximizing the rate of glucose production involves optimizing mixing, reactor holding time, and the time the feed is held in the reactor prior to commencement of membrane filtration and continuous operation. When we maximize glucose production rates it will require that we operate it at low glucose concentration in order to minimize the adverse effects of product inhibition. Consequently practical submerged membrane systems will require a combined sugar concentration step in order to concentrate the product sugar stream prior to fermentation.

Growth of floating-leaved and submerged plants in artificial co-cultured microcosms: morphological responses to various water fluctuation regimes

International Nuclear Information System (INIS)

Cao, Q.J.

2015-01-01

Hydrocharis dubia can alternate between a rooted floating-leaved and a free-floating form, so given increasingly frequent precipitation extremes, it is not expected to be more negatively impacted by rapid water fluctuations than by gradual ones and may adapt water fluctuations by alteration of life forms. However, the opposite may be true for Nymphoides peltata, with only a rooted floating-leaved form. We designed an experiment combining six water depth treatments (constant shallow, constant deep, and two rapidly and two gradually fluctuating treatments) with three speciescombinations (N. peltata H. dubia, N. peltata Ceratophyllum demersum, and H. dubia C. demersum) to investigate plant responses to depth fluctuations and their co-cultured species. The total mass of N. peltata was considerably lower in the rapidly- than in the gradually-fluctuating treatments. However, total mass of H. dubia in the rapidly-fluctuating treatments was similar to or higher than in the gradually-fluctuating ones. Rapid fluctuations had a negative impact on the growth of C. demersum than gradual fluctuating. The floating-leaved species demonstrated divergent adaptive strategies to different water fluctuation patterns. In addition to expanding leaf blades, H. dubia can adapt to changing water depths by changing its life form. However, N. peltata, which mainly relies on morphological plasticity, such as petiole elongation, to adapt to water rise may reduce its abundance in communities subjected to increasingly frequent floods. The growth of submerged C. demersum, either co-occurring with H. dubia or with N. peltata, may be repressed by high flooding rates. (author)

Submerged macrophytes mitigate direct and indirect insecticide effects in freshwater communities.

Science.gov (United States)

Brogan, William R; Relyea, Rick A

2015-01-01

Understanding how ecological interactions mitigate the impacts of perturbations such as pesticides in biological communities is an important basic and applied question for ecologists. In aquatic ecosystems, new evidence from microcosm experiments suggests that submerged macrophytes can buffer cladocerans from pulse exposures to the widely used insecticide malathion, and that mitigation increases with macrophyte density. However, whether these results scale up to more complex aquatic communities where ecological interactions such as competition can alter toxicity is unknown. Further, macrophyte abilities to mitigate different insecticide exposure scenarios (i.e. single versus repeated pulses) have never been tested. To address these gaps, we performed a factorial mesocosm experiment examining the influence of four macrophyte treatments (0, 10, 50, or 100 Elodea Canadensis shoots planted per mesocosm) crossed with three malathion exposure scenarios (no insecticide, single pulse, repeated pulses) on aquatic communities containing zooplankton, phytoplankton, periphyton, two snail species, and larval amphibians. In the absence of macrophytes, single malathion pulses caused short-term declines in cladoceran abundance followed by their rapid recovery, which precluded any indirect effects (i.e. trophic cascades). However, repeated malathion pulses caused cladoceran extinctions, resulting in persistent phytoplankton blooms and reduced abundance of one snail species. In contrast, with macrophytes present, even at low density, malathion had no effect on any taxa. We also discovered novel effects of macrophytes on the benthic food web. In the two highest macrophyte treatments, we observed trends of reduced periphyton biomass, decreased abundance of one snail species, and decreased amphibian time to and mass at metamorphosis. To our knowledge, this is the first evidence of negative submerged macrophyte effects on amphibians, a taxa of global conservation concern. Our findings

Submerged Macrophytes Mitigate Direct and Indirect Insecticide Effects in Freshwater Communities

Science.gov (United States)

Brogan, William R.; Relyea, Rick A.

2015-01-01

Understanding how ecological interactions mitigate the impacts of perturbations such as pesticides in biological communities is an important basic and applied question for ecologists. In aquatic ecosystems, new evidence from microcosm experiments suggests that submerged macrophytes can buffer cladocerans from pulse exposures to the widely used insecticide malathion, and that mitigation increases with macrophyte density. However, whether these results scale up to more complex aquatic communities where ecological interactions such as competition can alter toxicity is unknown. Further, macrophyte abilities to mitigate different insecticide exposure scenarios (i.e. single versus repeated pulses) have never been tested. To address these gaps, we performed a factorial mesocosm experiment examining the influence of four macrophyte treatments (0, 10, 50, or 100 Elodea Canadensis shoots planted per mesocosm) crossed with three malathion exposure scenarios (no insecticide, single pulse, repeated pulses) on aquatic communities containing zooplankton, phytoplankton, periphyton, two snail species, and larval amphibians. In the absence of macrophytes, single malathion pulses caused short-term declines in cladoceran abundance followed by their rapid recovery, which precluded any indirect effects (i.e. trophic cascades). However, repeated malathion pulses caused cladoceran extinctions, resulting in persistent phytoplankton blooms and reduced abundance of one snail species. In contrast, with macrophytes present, even at low density, malathion had no effect on any taxa. We also discovered novel effects of macrophytes on the benthic food web. In the two highest macrophyte treatments, we observed trends of reduced periphyton biomass, decreased abundance of one snail species, and decreased amphibian time to and mass at metamorphosis. To our knowledge, this is the first evidence of negative submerged macrophyte effects on amphibians, a taxa of global conservation concern. Our findings

Submerged macrophytes mitigate direct and indirect insecticide effects in freshwater communities.

Directory of Open Access Journals (Sweden)

William R Brogan

Full Text Available Understanding how ecological interactions mitigate the impacts of perturbations such as pesticides in biological communities is an important basic and applied question for ecologists. In aquatic ecosystems, new evidence from microcosm experiments suggests that submerged macrophytes can buffer cladocerans from pulse exposures to the widely used insecticide malathion, and that mitigation increases with macrophyte density. However, whether these results scale up to more complex aquatic communities where ecological interactions such as competition can alter toxicity is unknown. Further, macrophyte abilities to mitigate different insecticide exposure scenarios (i.e. single versus repeated pulses have never been tested. To address these gaps, we performed a factorial mesocosm experiment examining the influence of four macrophyte treatments (0, 10, 50, or 100 Elodea Canadensis shoots planted per mesocosm crossed with three malathion exposure scenarios (no insecticide, single pulse, repeated pulses on aquatic communities containing zooplankton, phytoplankton, periphyton, two snail species, and larval amphibians. In the absence of macrophytes, single malathion pulses caused short-term declines in cladoceran abundance followed by their rapid recovery, which precluded any indirect effects (i.e. trophic cascades. However, repeated malathion pulses caused cladoceran extinctions, resulting in persistent phytoplankton blooms and reduced abundance of one snail species. In contrast, with macrophytes present, even at low density, malathion had no effect on any taxa. We also discovered novel effects of macrophytes on the benthic food web. In the two highest macrophyte treatments, we observed trends of reduced periphyton biomass, decreased abundance of one snail species, and decreased amphibian time to and mass at metamorphosis. To our knowledge, this is the first evidence of negative submerged macrophyte effects on amphibians, a taxa of global conservation concern

Marine algal flora of submerged Angria Bank (Arabian Sea)

Digital Repository Service at National Institute of Oceanography (India)

Untawale, A.G.; Reddy, C.R.K.; Ambiye, V.

Submerged Angria Bank was surveyed for the deep water marine algal flora. About 57 species were reported from this bank for the first time. Rhodophyta dominated (30 species) followed by Chlorophyta (18 species) and Phaeophyta (9 species). A few...

Surface wave energy absorption by a partially submerged bio-inspired canopy.

Science.gov (United States)

Nové-Josserand, C; Castro Hebrero, F; Petit, L-M; Megill, W M; Godoy-Diana, R; Thiria, B

2018-03-27

Aquatic plants are known to protect coastlines and riverbeds from erosion by damping waves and fluid flow. These flexible structures absorb the fluid-borne energy of an incoming fluid by deforming mechanically. In this paper we focus on the mechanisms involved in these fluid-elasticity interactions, as an efficient energy harvesting system, using an experimental canopy model in a wave tank. We study an array of partially-submerged flexible structures that are subjected to the action of a surface wave field, investigating in particular the role of spacing between the elements of the array on the ability of our system to absorb energy from the flow. The energy absorption potential of the canopy model is examined using global wave height measurements for the wave field and local measurements of the elastic energy based on the kinematics of each element of the canopy. We study different canopy arrays and show in particular that flexibility improves wave damping by around 40%, for which half is potentially harvestable.

[Antimicrobial activity of Laetiporus sulphureus strains grown in submerged culture].

Science.gov (United States)

Ershova, E Iu; Tikhonova, O V; Lur'e, L M; Efremenkova, O V; Kamzolkina, O V; Dudnik, Iu V

2003-01-01

Cultural conditions for growth and fruit body formation were elaborated to four strains of Laetiporus sulphureus isolated from nature. All strains demonstrated antimicrobial activity against a wide spectrum of gram-positive and gram-negative bacteria during agar and submerged cultivation including methicillin-resistant strain of Staphylococcus aureus (MRSA) and glycopeptide-resistant strain of Leuconostoc mesenteroides. Antifungal activity was not found. The level of antimicrobial activity during submerged cultivation reached maximum after seven days of growth on specific medium with soybean meal and corn liquid; the next four weeks its increasing was not so manifested. Antimicrobial activity correlated with orange pigment secretion and cultural liquid acidification to pH 2.0-2.8 that indicates on acid nature of synthesized products.

Identification of a novel submergence response gene regulated by ...

African Journals Online (AJOL)

Tuoyo Aghomotsegin

2016-12-07

Dec 7, 2016 ... ... stress. Hormone ABA treatment induces, whereas GA treatment decreases, RS1 ... Key word: Rice (Oryza sativa L.), submergence, RNA-seq, Sub1A, abiotic stress. ... genes may interact with Sub1A-1 that are necessary for.

Comparison of the role of gibberellins and ethylene in response to submergence of two lowland rice cultivars, Senia and Bomba.

Science.gov (United States)

Dubois, Vincent; Moritz, Thomas; García-Martínez, José L

2011-02-15

We examined the gibberellin (GA) and ethylene regulation of submergence-induced elongation in seedlings of the submergence-tolerant lowland rice (Oryza sativa L.) cvs Senia and Bomba. Elongation was enhanced after germination to facilitate water escape and reach air. We found that submergence-induced elongation depends on GA because it was counteracted by paclobutrazol (an inhibitor of GA biosynthesis), an effect that was negated by GA(3). Moreover, in the cv Senia, submergence increased the content of active GA(1) and its immediate precursors (GA(53), GA(19) and GA(20)) by enhancing expression of several GA biosynthesis genes (OsGA20ox1 and -2, and OsGA3ox2), but not by decreasing expression of several OsGA2ox (GA inactivating genes). Senia seedlings, in contrast to Bomba seedlings, did not elongate in response to ethylene or 1-aminocyclopropane-1-carboxylic-acid (ACC; an ethylene precursor) application, and submergence-induced elongation was not reduced in the presence of 1-methylcyclopropene (1-MCP; an ethylene perception inhibitor). Ethylene emanation was similar in Senia seedlings grown in air and in submerged-grown seedlings following de-submergence, while it increased in Bomba. The expression of ethylene biosynthesis genes (OsACS1, -2 and -3, and OsACO1) was not affected in Senia, but expression of OsACS5 was rapidly enhanced in Bomba upon submergence. Our results support the conclusion that submergence elongation enhancement of lowland rice is due to alteration of GA metabolism leading to an increase in active GA (GA(1)) content. Interestingly, in the cv Senia, in contrast to cv Bomba, this was triggered through an ethylene-independent mechanism. Copyright © 2010 Elsevier GmbH. All rights reserved.

On the submerging of a spherical intruder into granular beds

Directory of Open Access Journals (Sweden)

Wu Chuan-Yu

2017-01-01

Full Text Available Granular materials are complex systems and their mechanical behaviours are determined by the material properties of individual particles, the interaction between particles and the surrounding media, which are still incompletely understood. Using an advanced discrete element method (DEM, we simulate the submerging process of a spherical projectile (an intruder into granular materials of various properties with a zero penetration velocity (i.e. the intruder is touching the top surface of the granular bed and released from stationary and examine its settling behaviour. By systematically changing the density and size of the intruder and the particle density (i.e. the density of the particles in the granular bed, we find that the intruder can sink deep into the granular bed even with a zero penetration velocity. Furthermore, we confirm that under certain conditions the granular bed can behave like a Newtonian liquid and the submerging intruder can reach a constant velocity, i.e. the terminal velocity, identical to the settling of a sphere in a liquid, as observed experimentally. A mathematical model is also developed to predict the maximum penetration depth of the intruder. The model predictions are compared with experimental data reported in the literature,good agreement was obtained, demonstrating the model can accurately predict the submerging behaviour of the intruder in the granular media.

Restoration of Shallow Lakes in Subtropical and Tropical China: Response of Nutrients and Water Clarity to Biomanipulation by Fish Removal and Submerged Plant Transplantation

Directory of Open Access Journals (Sweden)

Jinlei Yu

2016-10-01

Full Text Available Fish removal has been used to restore temperate lakes, and positive effects on ecological state and water clarity have frequently been recorded in many lakes. Recently, a supplementary measure, transplantation of submerged macrophytes after fish removal, has been applied to restore warm Chinese shallow lakes in order to compensate for the expected lack of increasing grazing control of phytoplankton after the biomanipulation. These measures have successfully shifted turbid warm lakes to a clear water state, but little is known about the responses to restoration of key physico-chemical variables. We analyzed the seasonal variation in nutrient concentrations in two subtropical and one tropical biomanipulated shallow Chinese lakes subjected to restoration. In all three lakes, a marked decline occurred in the concentrations of lake total nitrogen (TN, total phosphorus (TP, total suspended solids (TSS, and chlorophyll a (Chl a, while the transparency (SD:WD ratio, Secchi depth to water depth ratio increased. A clear water state was established, lasting so far for 7 to 23 months, and TN, TP, Chl a, and TSS levels in the three restored lakes decreased to, on average, 49%, 58%, 41%, and 18% of the level prior to restoration and/or the level in a reference lake, respectively, while the annual mean SD:WD ratio exhibited a 1.5–4 fold increase. In conclusion, lake restoration by transplantation of submerged macrophytes after fish removal had major positive effects on the physico-chemical variables in our study lakes. However, continuous control of omnivorous and herbivorous fish biomass is recommended as the fish typically present in warm, shallow lakes to some extent feed on submerged macrophytes, when available.

The distribution of submersed aquatic vegetation and water lettuce in the fresh and oligohaline tidal Potomac River, 2007

Science.gov (United States)

Campbell, Sarah Hunter; Rybicki, Nancy B.; Schenk, Edward R.

2015-01-01

Surveys documenting the composition of species of submersed aquatic vegetation (SAV) have been conducted in the Potomac River for decades. These surveys can help managers assess the proportion of native and exotic plants in the river or can be used to determine relationships between native and exotic plants, environmental conditions, and wildlife. SAV coverage increased from 2005 to 2007 throughout the fresh and oligohaline study area. The 2007 survey documented here determined that eleven species of SAV were present. The abundance of the exotic species Hydrilla verticillata (hydrilla) was relatively low, and species diversity was relatively high compared to previous years. The survey also revealed a new population of the invasive, floating aquatic plant Pistia stratiotes (water lettuce). In 2007, water lettuce, the latest exotic aquatic plant to be found in the fresh to oligohaline portion of the Potomac River, was most abundant in Mattawoman Creek, Charles County, Maryland. However, it was not observed in the fresh to oligohaline portion of the Potomac River in the summer of 2008. An understanding of the distribution of SAV species and factors governing the abundance of native and invasive aquatic species is enhanced by long-term surveys.

Supporting Calculations For Submerged Bed Scrubber Condensate Disposal Preconceptual Study

International Nuclear Information System (INIS)

Pajunen, A. J.; Tedeschi, A. R.

2012-01-01

This document provides supporting calculations for the preparation of the Submerged Bed Scrubber Condensate Disposal Preconceptual Study report. The supporting calculations include equipment sizing, Hazard Category determination, and LAW Melter Decontamination Factor Adjustments

Supporting Calculations For Submerged Bed Scrubber Condensate Disposal Preconceptual Study

Energy Technology Data Exchange (ETDEWEB)

Pajunen, A. J.; Tedeschi, A. R.

2012-09-18

This document provides supporting calculations for the preparation of the Submerged Bed Scrubber Condensate Disposal Preconceptual Study report The supporting calculations include equipment sizing, Hazard Category determination, and LAW Melter Decontamination Factor Adjustments.

Automatic welding processes for reactor coolant pipes used in PWR type nuclear power plant

International Nuclear Information System (INIS)

Hamada, T.; Nakamura, A.; Nagura, Y.; Sakamoto, N.

1979-01-01

The authors developed automatic welding processes (submerged arc welding process and TIG welding process) for application to the welding of reactor coolant pipes which constitute the most important part of the PWR type nuclear power plant. Submerged arc welding process is suitable for flat position welding in which pipes can be rotated, while TIG welding process is suitable for all position welding. This paper gives an outline of the two processes and the results of tests performed using these processes. (author)

Corncob hydrolysate, an efficient substrate for Monascus pigment production through submerged fermentation.

Science.gov (United States)

Zhou, Zhongxin; Yin, Zheng; Hu, Xiaoqing

2014-01-01

Monascus pigment has traditionally been produced by the fermentation of Monascus using rice powder or glucose as a culture substrate. Submerged fermentation can produce stable Monascus pigment yield and control the accumulation of the by-product, citrinin, which can then be more easily removed. To reduce the cost of Monascus submerged fermentation, the feasibility of corncob hydrolysate as an alternative substrate was investigated. Results showed that, when compared with a conventional glucose medium, the corncob hydrolysate medium produced an equivalent pigment yield without stimulating citrinin accumulation. Furthermore, the corncob hydrolysate medium and cultivation conditions were optimized to enhance pigment production and decrease citrinin synthesis. When Monascus sp. was cultured under dark conditions in the presence of caprylic acid, pigment production was increased to 25.8 ± 0.8 UA500 /mL, which was higher than that achieved in a glucose medium (24.0 ± 0.9 UA500 /mL), and those obtained in previously reported Monascus submerged fermentations using the same yield unit; on the other hand, citrinin accumulation was decreased to 26.2 ± 1.9 µg/L, which was significantly lower than that generated in the glucose control (44.3 ± 2.2 µg/L) and in those previously reported fermentations. Thus, corncob hydrolysate was proved to be an efficient alternative substrate for Monascus pigment production through submerged fermentation, which showed significant advantages over a conventional glucose substrate. © 2014 International Union of Biochemistry and Molecular Biology, Inc.

Biological control of phytoplankton by the subtropical submerged macrophytes Egeria densa and Potamogeton illinoensis: a mesocosm study

NARCIS (Netherlands)

Vanderstukken, M.; Mazzeo, N.; Colen, W.; Declerck, S.A.J.; Muylaert, K.

2011-01-01

1. In temperate regions, submerged macrophytes can hamper phytoplankton blooms. Such an effect could arise directly, for instance via allelopathy, or indirectly, via competition for nutrients or the positive interaction between submerged macrophytes and zooplankton grazing. However, there is some

Effects of CO 2 concentration and light intensity on photosynthesis of a rootless submerged plant, Ceratophyllumdemersum L., used for aquatic food production in bioregenerative life support systems

Science.gov (United States)

Kitaya, Y.; Okayama, T.; Murakami, K.; Takeuchi, T.

In addition to green microalgae, aquatic higher plants are likely to play an important role in aquatic food production modules in bioregenerative systems for producing feed for fish, converting CO 2 to O 2 and remedying water quality. In the present study, the effects of culture conditions on the net photosynthetic rate of a rootless submerged plant, Ceratophyllum demersum L., was investigated to determine the optimum culture conditions for maximal function of plants in food production modules including both aquatic plant culture and fish culture systems. The net photosynthetic rate in plants was determined by the increase in dissolved O 2 concentrations in a closed vessel containing a plantlet and water. The water in the vessel was aerated sufficiently with a gas containing a known concentration of CO 2 gas mixed with N 2 gas before closing the vessel. The CO 2 concentrations in the aerating gas ranged from 0.3 to 10 mmol mol -1. Photosynthetic photon flux density (PPFD) in the vessel ranged from 0 (dark) to 1.0 mmol M -2 s -1, which was controlled with a metal halide lamp. Temperature was kept at 28°C. The net photosynthetic rate increased with increasing PPFD levels and was saturated at 0.2 and 0.5 mmol m -2 s -1 PPFD under CO 2 levels of 1.0 and 3.0 mmol mol -1, respectively. The net photosynthetic rate increased with increasing CO 2 levels from 0.3 to 3.0 mmol mol -1 showing the maximum value, 75 nmolO 2 gDW -1 s -1, at 2-3 mmol mol -1 CO 2 and gradually decreased with increasing CO 2 levels from 3.0 to 10 mmol mol -1. The results demonstrate that C. demersum could be an efficient CO 2 to O 2 converter under a 2.0 mmol mol -1 CO 2 level and relatively low PPFD levels in aquatic food production modules.

Oxidative stress responses of submerged macrophyte Vallisneria asiatica to different concentrations of cyanobacteria

Science.gov (United States)

Kang, Caixia; Kuba, Takahiro; Hao, Aimin; Iseri, Yasushi; Li, Chunjie; Zhang, Zhenjia

2015-03-01

In a 10-day aquarium experiment, this investigation examines macrophyte restoration in eutrophic Lake Taihu, the physiological effects of different plant biomass levels and of increasing natural cyanobacterial concentrations on a submerged macrophyte, Vallisneria asiatica. Cyanobacterial stress suppressed the superoxide dismutase (SOD) activity of the plant's leaves and induced the catalase (CAT) and peroxidase (POD) activities of its roots. The soluble protein content in V. asiatica decreased with an increase in natural cyanobacterial concentrations, whereas the malonaldehyde (MDA) increased significantly at chlorophyll a (Chl a) concentrations of 222 and 262 μg/L in water. V. asiatica adapted to the stress caused by cyanobacterial concentrations by adjusting its antioxidant defense system to remove the excessive reactive oxygen species when the algal Chl a concentration was >109 μg/L. Additionally, high biomass of V. asiatica (2 222 g FW/m2) can inhibit the reproduction of cyanobacteria more significantly than low biomass (1 111 g FW/m2). High biomass of V. asiatica increased the oxidative stress in an individual plant when the initial Chl a concentration in the water reached 222 and 262 μg/L, as expressed by the increased MDA in leaves, compared with low biomass of V. asiatica. This provides a basis for controlling cyanobacterial concentrations and V. asiatica biomass for the recovery of V. asiatica in eutrophic Lake Taihu.

Submergence rice cultivation in southern Bangladesh: farmers opinion and adaptations practices

Directory of Open Access Journals (Sweden)

AKM Abdul Ahad Biswas

2015-12-01

Full Text Available Rice productivity in coastal Bangladesh is lower than the national average and total coastal area is considered to be submergence-prone and higher vulnerable in July to January cropping season. The selected study areas are Kalapara and Patuakhali Sadar Upazila that are too vulnerable to agriculture practices. Field survey was conducted during 01st June to 30th July, 2015 to investigate the impact of submergence on Aman rice cultivation (ARC, existing adopted local adaptation practices with impacts and options to address the submergence problem. Primary data was collected through Focus Group Discussion (FGD, Individual Interview and Key Informant Interview methods and secondary data was collected from different secondary sources. A well-structured pretested questionnaire schedule was developed keeping in mind the objectives and variables under this study. After cyclone SIDR and AILA devastation, the rate of traditional ARC is decreasing every year and in 2015 it was 26.51%. Recently farmers have adopted new cropping practices and strategies like modern ARC in Aman season as single crop; Boro-Aus-Aman season as triple crop and Aus-Aman season as double crop are practicing. Approximately all farmers have adopted to grow stress tolerant rice varieties (STRV; farmer’s curiosities to familiar with and to have the STRV are encouraging. Farmers were fully adopted BRRIdhan52 rice cultivation with positive perceptions of higher yield and lower production cost. Therefore it can be concluded that the intensity of adoption of adaptation and mitigation measures are significantly influenced positively by the STRV yield capability; farmer’s participation in intervention programs; livelihood diversification; frequency of extension personnel contact; submergence and inundation characteristics; tolerance attributes of STRV and availability of STRV cultivation information.International Journal of Environment Vol.4(4 2015: 100-113

Aquatic adventitious roots of the wetland plant Meionectes brownii can photosynthesize

DEFF Research Database (Denmark)

Rich, Sarah Meghan; Ludwig, Martha; Pedersen, Ole

2011-01-01

• Many wetland plants produce aquatic adventitious roots from submerged stems. Aquatic roots can form chloroplasts, potentially producing endogenous carbon and oxygen. Here, aquatic root photosynthesis was evaluated in the wetland plant Meionectes brownii, which grows extensive stem-borne aquatic...... roots during submergence. • Underwater photosynthetic light and CO(2) response curves were determined for aquatic-adapted leaves, stems and aquatic roots of M. brownii. Oxygen microelectrode and (14)CO(2)-uptake experiments determined shoot inputs of O(2) and photosynthate into aquatic roots. • Aquatic...... adventitious roots contain a complete photosynthetic pathway. Underwater photosynthetic rates are similar to those of stems, with a maximum net photosynthetic rate (P(max)) of 0.38 µmol O(2) m(-2) s(-1); however, this is c. 30-fold lower than that of aquatic-adapted leaves. Under saturating light with 300 mmol...

Rhode Island, Connecticut, New York, and New Jersey ESI: HABITATS (Habitat and Plant Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for eelgrass, macroalgae, submerged aquatic vegetation, and rare terrestrial plants in coastal Rhode...

Effects of submerged and anaerobic fermentations on cassava flour ...

African Journals Online (AJOL)

Cassava tubers for processing into cassava flour, Lafun a Nigerian locally fermented product was subjected to two different types of fermentations: submerged and anaerobic fermentation for 72 h. Physicochemical changes that occurred during fermentation and their influence on the functional, rheological and sensory ...

Effects of submerged vegetation on water clarity across climates

NARCIS (Netherlands)

Kosten, S.; Lacerot, G.; Jeppesen, E.; Motta Marques, D.M.L.; Nes, van E.H.; Mazzeo, N.; Scheffer, M.

2009-01-01

A positive feedback between submerged vegetation and water clarity forms the backbone of the alternative state theory in shallow lakes. The water clearing effect of aquatic vegetation may be caused by different physical, chemical, and biological mechanisms and has been studied mainly in temperate

Submerged Aquatic Vegetation of Bogue Sound, North Carolina 1992 Geoform

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — During 1992, 1:20,000 scale aerial photography for Bogue Sound, North Carolina was collected as part of an effort to map submerged aquatic vegetation (SAV) in...

Submerged Aquatic Vegetation of Bogue Sound, North Carolina 1992 Geodatabase

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — During 1992, 1:20,000 scale aerial photography for Bogue Sound, North Carolina was collected as part of an effort to map submerged aquatic vegetation (SAV) in...

Submerged Aquatic Vegetation of Bogue Sound, North Carolina 1992 Substrate

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — During 1992, 1:20,000 scale aerial photography for Bogue Sound, North Carolina was collected as part of an effort to map submerged aquatic vegetation (SAV) in...

Proteomic analysis of extracellular proteins from Aspergillus oryzae grown under submerged and solid-state culture conditions.

Science.gov (United States)

Oda, Ken; Kakizono, Dararat; Yamada, Osamu; Iefuji, Haruyuki; Akita, Osamu; Iwashita, Kazuhiro

2006-05-01

Filamentous fungi are widely used for the production of homologous and heterologous proteins. Recently, there has been increasing interest in Aspergillus oryzae because of its ability to produce heterologous proteins in solid-state culture. To provide an overview of protein secretion by A. oryzae in solid-state culture, we carried out a comparative proteome analysis of extracellular proteins in solid-state and submerged (liquid) cultures. Extracellular proteins prepared from both cultures sequentially from 0 to 40 h were subjected to two-dimensional electrophoresis, and protein spots at 40 h were identified by peptide mass fingerprinting using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. We also attempted to identify cell wall-bound proteins of the submerged culture. We analyzed 85 spots from the solid-state culture and 110 spots from the submerged culture. We identified a total of 29 proteins, which were classified into 4 groups. Group 1 consisted of extracellular proteins specifically produced in the solid-state growth condition, such as glucoamylase B and alanyl dipeptidyl peptidase. Group 2 consisted of extracellular proteins specifically produced in the submerged condition, such as glucoamylase A (GlaA) and xylanase G2 (XynG2). Group 3 consisted of proteins produced in both conditions, such as xylanase G1. Group 4 consisted of proteins that were secreted to the medium in the solid-state growth condition but trapped in the cell wall in the submerged condition, such as alpha-amylase (TAA) and beta-glucosidase (Bgl). A Northern analysis of seven genes from the four groups suggested that the secretion of TAA and Bgl was regulated by trapping these proteins in the cell wall in submerged culture and that secretion of GlaA and XynG2 was regulated at the posttranscriptional level in the solid-state culture.

Improved, Low-Stress Economical Submerged Pipeline

Science.gov (United States)

Jones, Jack A.; Chao, Yi

2011-01-01

A preliminary study has shown that the use of a high-strength composite fiber cloth material may greatly reduce fabrication and deployment costs of a subsea offshore pipeline. The problem is to develop an inexpensive submerged pipeline that can safely and economically transport large quantities of fresh water, oil, and natural gas underwater for long distances. Above-water pipelines are often not feasible due to safety, cost, and environmental problems, and present, fixed-wall, submerged pipelines are often very expensive. The solution is to have a submerged, compliant-walled tube that when filled, is lighter than the surrounding medium. Some examples include compliant tubes for transporting fresh water under the ocean, for transporting crude oil underneath salt or fresh water, and for transporting high-pressure natural gas from offshore to onshore. In each case, the fluid transported is lighter than its surrounding fluid, and thus the flexible tube will tend to float. The tube should be ballasted to the ocean floor so as to limit the motion of the tube in the horizontal and vertical directions. The tube should be placed below 100-m depth to minimize biofouling and turbulence from surface storms. The tube may also have periodic pumps to maintain flow without over-pressurizing, or it can have a single pump at the beginning. The tube may have periodic valves that allow sections of the tube to be repaired or maintained. Some examples of tube materials that may be particularly suited for these applications are non-porous composite tubes made of high-performance fibers such as Kevlar, Spectra, PBO, Aramid, carbon fibers, or high-strength glass. Above-ground pipes for transporting water, oil, and natural gas have typically been fabricated from fiber-reinforced plastic or from more costly high-strength steel. Also, previous suggested subsea pipeline designs have only included heavy fixed-wall pipes that can be very expensive initially, and can be difficult and expensive

Analysis of submerged implant towards mastication load using 3D finite element method (FEM)

OpenAIRE

Widia Hafsyah Sumarlina Ritonga; Janti Rusjanti; Nunung Rusminah; Aldilla Miranda; Tatacipta Dirgantara

2016-01-01

Introduction: The surgical procedure for implantation of a surgical implant comprising a stage for the implant design nonsubmerged and two stages for submerged. Submerged implant design often used in Faculty of Dentistry Universitas Padjadjaran because it is safer in achieving osseointegration. This study was conducted to evaluate the failure of dental implant based on location and the value of internal tensiones as well as supporting tissues when given mastication load by using the 3D Finite...

Mowing Submerged Macrophytes in Shallow Lakes with Alternative Stable States: Battling the Good Guys?

Science.gov (United States)

Kuiper, Jan J.; Verhofstad, Michiel J. J. M.; Louwers, Evelien L. M.; Bakker, Elisabeth S.; Brederveld, Robert J.; van Gerven, Luuk P. A.; Janssen, Annette B. G.; de Klein, Jeroen J. M.; Mooij, Wolf M.

2017-04-01

Submerged macrophytes play an important role in maintaining good water quality in shallow lakes. Yet extensive stands easily interfere with various services provided by these lakes, and harvesting is increasingly applied as a management measure. Because shallow lakes may possess alternative stable states over a wide range of environmental conditions, designing a successful mowing strategy is challenging, given the important role of macrophytes in stabilizing the clear water state. In this study, the integrated ecosystem model PCLake is used to explore the consequences of mowing, in terms of reducing nuisance and ecosystem stability, for a wide range of external nutrient loadings, mowing intensities and timings. Elodea is used as a model species. Additionally, we use PCLake to estimate how much phosphorus is removed with the harvested biomass, and evaluate the long-term effect of harvesting. Our model indicates that mowing can temporarily reduce nuisance caused by submerged plants in the first weeks after cutting, particularly when external nutrient loading is fairly low. The risk of instigating a regime shift can be tempered by mowing halfway the growing season when the resilience of the system is highest, as our model showed. Up to half of the phosphorus entering the system can potentially be removed along with the harvested biomass. As a result, prolonged mowing can prevent an oligo—to mesotrophic lake from becoming eutrophic to a certain extent, as our model shows that the critical nutrient loading, where the lake shifts to the turbid phytoplankton-dominated state, can be slightly increased.

Production and Characterization of Lipases by Two New Isolates of Aspergillus through Solid-State and Submerged Fermentation

Science.gov (United States)

Colla, Luciane Maria; Ficanha, Aline M. M.; Rizzardi, Juliana; Bertolin, Telma Elita; Reinehr, Christian Oliveira; Costa, Jorge Alberto Vieira

2015-01-01

Due to the numerous applications of lipases in industry, there is a need to study their characteristics, because lipases obtained from different sources may present different properties. The aim of this work was to accomplish the partial characterization of lipases obtained through submerged fermentation and solid-state fermentation by two species of Aspergillus. Fungal strains were isolated from a diesel-contaminated soil and selected as good lipases producers. Lipases obtained through submerged fermentation presented optimal activities at 37°C and pH 7.2 and those obtained through solid-state fermentation at 35°C and pH 6.0. The enzymes produced by submerged fermentation were more temperature-stable than those obtained by solid-state fermentation, presenting 72% of residual activity after one hour of exposition at 90°C. Lipases obtained through submerged fermentation had 80% of stability in acidic pH and those obtained through solid-state fermentation had stability greater than 60% in alkaline pH. PMID:26180809

Production and Characterization of Lipases by Two New Isolates of Aspergillus through Solid-State and Submerged Fermentation

Directory of Open Access Journals (Sweden)

Luciane Maria Colla

2015-01-01

Full Text Available Due to the numerous applications of lipases in industry, there is a need to study their characteristics, because lipases obtained from different sources may present different properties. The aim of this work was to accomplish the partial characterization of lipases obtained through submerged fermentation and solid-state fermentation by two species of Aspergillus. Fungal strains were isolated from a diesel-contaminated soil and selected as good lipases producers. Lipases obtained through submerged fermentation presented optimal activities at 37°C and pH 7.2 and those obtained through solid-state fermentation at 35°C and pH 6.0. The enzymes produced by submerged fermentation were more temperature-stable than those obtained by solid-state fermentation, presenting 72% of residual activity after one hour of exposition at 90°C. Lipases obtained through submerged fermentation had 80% of stability in acidic pH and those obtained through solid-state fermentation had stability greater than 60% in alkaline pH.

Radiocarbon measurements on submerged forest floating chronologies

International Nuclear Information System (INIS)

Campbell, J.A.; Baxter, M.S.

1979-01-01

It is stated that the submerged forests along the west coast of England and Wales provide a unique source of wood for radiocarbon/ dendrochronological studies. 14 C age determinations are reported on sequential growth increments from three 'gloating' chronologies. A sampling frequency of approximately 10 samples per century was used. Fluctuations in atmospheric 14 C levels of 2 to 3% over several decades can occur, these variations being superimposed on a smoothly changing trend. (author)

Comparison of solid-state and submerged-state fermentation for the bioprocessing of switchgrass to ethanol and acetate by Clostridium phytofermentans.

Science.gov (United States)

Jain, Abhiney; Morlok, Charles K; Henson, J Michael

2013-01-01

The conversion of sustainable energy crops using microbiological fermentation to biofuels and bioproducts typically uses submerged-state processes. Alternatively, solid-state fermentation processes have several advantages when compared to the typical submerged-state processes. This study compares the use of solid-state versus submerged-state fermentation using the mesophilic anaerobic bacterium Clostridium phytofermentans in the conversion of switchgrass to the end products of ethanol, acetate, and hydrogen. A shift in the ratio of metabolic products towards more acetate and hydrogen production than ethanol production was observed when C. phytofermentans was grown under solid-state conditions as compared to submerged-state conditions. Results indicated that the end product concentrations (in millimolar) obtained using solid-state fermentation were higher than using submerged-state fermentation. In contrast, the total fermentation products (in weight of product per weight of carbohydrates consumed) and switchgrass conversion were higher for submerged-state fermentation. The conversion of xylan was greater than glucan conversion under both fermentation conditions. An initial pH of 7 and moisture content of 80 % resulted in maximum end products formation. Scanning electron microscopy study showed the presence of biofilm formed by C. phytofermentans growing on switchgrass under submerged-state fermentation whereas bacterial cells attached to surface and no apparent biofilm was observed when grown under solid-state fermentation. To our knowledge, this is the first study reporting consolidated bioprocessing of a lignocellulosic substrate by a mesophilic anaerobic bacterium under solid-state fermentation conditions.

Removal of Metal Nanoparticles Colloidal Solutions by Water Plants

Science.gov (United States)

Olkhovych, Olga; Svietlova, Nataliia; Konotop, Yevheniia; Karaushu, Olena; Hrechishkina, Svitlana

2016-11-01

The ability of seven species of aquatic plants ( Elodea canadensis, Najas guadelupensis, Vallisneria spiralis L., Riccia fluitans L., Limnobium laevigatum, Pistia stratiotes L., and Salvinia natans L.) to absorb metal nanoparticles from colloidal solutions was studied. It was established that investigated aquatic plants have a high capacity for removal of metal nanoparticles from aqueous solution (30-100%) which indicates their high phytoremediation potential. Analysis of the water samples content for elements including the mixture of colloidal solutions of metal nanoparticles (Mn, Cu, Zn, Ag + Ag2O) before and after exposure to plants showed no significant differences when using submerged or free-floating hydrophytes so-called pleuston. However, it was found that the presence of submerged hydrophytes in aqueous medium ( E. canadensis, N. guadelupensis, V. spiralis L., and R. fluitans L.) and significant changes in the content of photosynthetic pigments, unlike free-floating hydrophytes ( L. laevigatum, P. stratiotes L., S. natans L.), had occur. Pleuston possesses higher potential for phytoremediation of contaminated water basins polluted by metal nanoparticles. In terms of removal of nanoparticles among studied free-floating hydrophytes, P. stratiotes L. and S. natans L. deserve on special attention.

Benthic Bacterial Diversity in Submerged Sinkhole Ecosystems▿ †

Science.gov (United States)

Nold, Stephen C.; Pangborn, Joseph B.; Zajack, Heidi A.; Kendall, Scott T.; Rediske, Richard R.; Biddanda, Bopaiah A.

2010-01-01

Physicochemical characterization, automated ribosomal intergenic spacer analysis (ARISA) community profiling, and 16S rRNA gene sequencing approaches were used to study bacterial communities inhabiting submerged Lake Huron sinkholes inundated with hypoxic, sulfate-rich groundwater. Photosynthetic cyanobacterial mats on the sediment surface were dominated by Phormidium autumnale, while deeper, organically rich sediments contained diverse and active bacterial communities. PMID:19880643

Effects of Co2 Concentrations and light intensity on photosynthesis of a rootless submerged plant, ceratophyllum demersum L., used for aquatic food production in bioregenerative life support systems

Science.gov (United States)

Kitaya, Y.; Okayama, T.; Murakami, K.; Takeuchi, T.

Aquatic higher plants are likely to play an important role in aquatic food production modules in bioregenerative systems for producing feeds for fish, converting CO2 to O2 and remedying water quality in addition to green microalgae. In the present study, the effects of culture conditions on the net photosynthetic rate of a rootless submerged plant, Ceratophyllum demersum L., was investigated to determine the optimum culture conditions for plant function in aquatic food production modules including both plant culture and fish culture systems . The net photosynthetic rate in plants was determined by the increase in dissolved O2 concentrations in a closed vessel containing a plantlet and water. The water in the vessel was aerated sufficiently with a gas containing a known level CO 2 gas mixed with N2 gas before closing the vessel. The CO 2 concentrations in the aerating gas ranged from 0.3 to 100 mmol mol-1 . Photosynthetic photon flux density (PPFD) in the vessel ranged from 0 (dark) to 1.0 mmol m-2 s-1 , which was controlled with a metal halide lamp. Temperature was kept at 28 C. The net photosynthetic rate increased with increasing PPFD levels and was saturated at 0.2 and 0.5 mmol m-2 s-1 PPFD under CO 2 levels of 1.0 and 3.0 mmol mol-1 , respectively. The net photosynthetic rate increased with increasing CO2 levels from 0.3 to 3.0 mmol mol-1 showing the maximum value, 70 nmolO 2 gDW s at 3.0 mmol mol-1 CO2 and gradually decreased with increasing CO 2 levels from 3.0 to 100 mmol mol-1 . The results demonstrate that Ceratophyllum demersum L. could be an efficient CO 2 to O2 converter under a 3.0 mmol mol-1 CO2 level and relatively low PPFD levels in aquatic food production modules.

Numerical simulation for submerged body fitted with hydrofoil by boundary element method; Kyokai yosoho ni yoru yokutsuki bossuitai mawari no nagare keisan

Energy Technology Data Exchange (ETDEWEB)

Masuda, S.; Kasahara, Y.; Ashidate, I. [NKK Corp., Tokyo (Japan)

1996-12-31

In a high-speed boat of a type using hydrofoils, lifting force increases in proportion to square of its length, while displacement is proportional to the third power. Therefore, an idea has come up that speed of a large boat may be increased by combining the hydrofoils with a submerged body. In other words, the idea is to levitate a ship by using composite support consisting of buoyancy of the submerged body and lifting force caused by the hydrofoils. Insufficiency of the lifting force may be complemented by the buoyancy of the submerged body which increases in an equivalent rate as that in the displacement. However, combining a submerged body with hydrofoils render a problem that lifting force for hydrofoils decreases because of interactions among the submerged body, hydrofoils, and free surface. Therefore, assuming a model of a submerged body with a length of 85 m cruising at 40 kt, analysis was given on decrease in lifting force for hydrofoils due to interactions between the submerged and lifting body and free surface by using the boundary element method. As a result, it was verified that the lifting force for the hydrofoils decreases as a result of creation of a flow that decreases effective angle of attach of the hydrofoils. It was also made clear that making the submerging depth greater reduces the decrease in the lifting force. 9 refs., 14 figs., 1 tab.

Behaviour of tritium in the plant domain

International Nuclear Information System (INIS)

Krishnamoorthy, T.M.; Iyengar, T.S.; Soman, S.D.

1979-01-01

An attempt is made to review in three different ways the present status regarding the uptake, retention and release patterns of plants of different trophic levels exposed to a tritiated atmosphere. The mean residence time for the first major component is found to be within 1-12 days for all the terrestrial vegetations. The second and the third components form only a small fraction of the total tritium uptake and show significantly different mean residence times. The aquatic plant, Hydrilla verticellata, also shows very small residence time for the first component (0.4 h). An isotopic discrimination of about 30-40% against the incorporation of tissue-bound tritium (TBT) is found in some algal and aquatic species, and this is enhanced to as high as 90-99% for the terrestrial vegetations. When conditions of constant specific activity are maintained, even for the terrestrial vegetations high specific activity ratios are obtained in the few cases cited. The nucleic acid fraction has shown relative specific activity ratios of 0.37 and 1.0 for pea seedlings and algae respectively. In maize, though carbohydrate is a major fraction fat has shown maximum fixation of TBT. Mathematical resolution procedures to determine the mean residence times for TFWT/TBT fractions either from separated or composite sample fractions have been reviewed. TFWT time-activity profiles are built up for succulent plants from diffusion, xylem flow and the utilization of TFWT in the synthesis of TBT. A good agreement between the calculated and experimental values is obtained using molecular diffusion coefficients for succulent plants. The applicability of this concept for larger trees is discussed

Cathodic disbonding of organic coatings on submerged steel

Energy Technology Data Exchange (ETDEWEB)

Knudsen, Ole oeystein

1998-12-31

In offshore oil production, submerged steel structures are commonly protected by an organic coating in combination with cathodic protection. The main advantage is that the coating decreases the current demand for cathodic protection. But the coating degrades with time. This thesis studies one of the most important mechanisms for coating degradation in seawater, cathodic disbonding. Seven commercial coatings and two model coatings with various pigmentations have been studied. Parameter studies, microscopy and studies of free films were used in the mechanism investigations. Exposure to simulated North Sea conditions was used in the performance studies. The effect of aluminium and glass barrier pigments on cathodic disbonding was investigated. The mechanism for the effect of the aluminium pigments on cathodic disbonding was also investigated. The transport of charge and oxygen to the steel/coating interface during cathodic disbonding was studied for two epoxy coatings. Cathodic disbonding, blistering and current demand for cathodic protection was measured for nine commercial coatings for submerged steel structures, using the ASTM-G8 standard test and a long term test under simulated North Sea conditions. The relevance of the ASTM-G8 test as a prequalification test was evaluated. 171 refs., 40 figs., 6 tabs.

Tidal Power Potential in the Submerged Channels of Dar es

African Journals Online (AJOL)

on the tidal plateau, shallow water area on the sand banks and in the submerged channels, using self—recording .... in a Cartesian frame where iz is directed towards the vertical, ix points ..... Bongoyo, there is a 15 m deep channel that passes.

Wave energy absorption by a submerged air bag connected to a rigid float

DEFF Research Database (Denmark)

Kurniawan, Adi; Chaplin, J. R.; Hann, M. R.

2017-01-01

A new wave energy device features a submerged ballasted air bag connected at the top to a rigid float. Under wave action, the bag expands and contracts, creating a reciprocating air flow through a turbine between the bag and another volume housed within the float. Laboratory measurements are gene......A new wave energy device features a submerged ballasted air bag connected at the top to a rigid float. Under wave action, the bag expands and contracts, creating a reciprocating air flow through a turbine between the bag and another volume housed within the float. Laboratory measurements...

[Isolation, Purification and Identification of Antialgal Activity Substances of Ethyl Acetate Extracts from the Submerged Macrophytes Potamogeton crispus].

Science.gov (United States)

Sun, Ying-ying; Su, Zhen-xia; Pu, Yin-fang; Xiao, Hui; Wang, Chang-hai

2015-10-01

Previous studies showed that ethyl acetate extracts from the submerged macrophytes Potamogeton crispus can significantly inhibit the growth of Karenia mikimitoi. Further, two antialgal activity compounds (1-2) were successfully isolated from this submerged macrophytes through a combination of silica gel column chromagraphy and repeated preparative thin-layer chromatography in this paper. These two antialgal activity compounds exhibited antialgal active against Karenia mikimitoi. Furthermore, their structure were identified on the basis of spectroscopic data: one flavonid named Trichodermatides B, and one alkaloid named 2-methylheptylisonicotinate. These two compounds were for the first time isolated from both Potamogeton crispus and submerged macrophytes.

Anaerobe-Aerobe Submerged Biofilter Technology for Domestic Waste Water Treatment

International Nuclear Information System (INIS)

Nusa-Idaman-Said

2000-01-01

Water pollution in the big cities in Indonesia, especially in DKI Jakarta has shown serious problems. One of the potential sources of water pollution is domestic wastewater that is wastewater from kitchens, laundry, bathing and toilets. These problems have become more serious since the spreads of sewerage systems are still low, so that domestic, institutional and commercial wastewater cause severe water pollution in many rivers or shallow ground water. Bases on the fact that the progress of development of sewerage system is still low, it is important to develop low cost technology for individual house hold or semi communal wastewater treatment such as using anaerobic and aerobic submerged biofilter. This paper describes alternative technology for treatment of household wastewater or organic wastewater using anaerobic and aerobic submerged biofilter. Using this technology can decrease BOD, COD and Suspended Solids (SS) concentration more than 90 %. (author)

Aquatic macrophytes in the large, sub-tropical Itaipu Reservoir, Brazil.

Science.gov (United States)

Mormul, Roger Paulo; Ferreira, Fernando Alves; Michelan, Thaisa Sala; Carvalho, Priscilla; Silveira, Marcio José; Thomaz, Sidinei Magela

2010-12-01

In the last three decades, rapid assessment surveys have become an important approach for measuring aquatic ecosystem biodiversity. These methods can be used to detect anthropogenic impacts and recognize local or global species extinctions. We present a floristic survey of the aquatic macrophytes along the Brazilian margin of the Itaipu Reservoir conducted in 2008 and compare this with a floristic survey conducted ten years earlier. We used ordination analysis to determine whether assemblage composition differed among reservoir arms. Macrophyte species were sampled in each of the 235 sampling stations using a boat, which was positioned inside three places of each macrophyte stand to record species and search for small plants. We also collected submerged plants using a rake with the boat moving at constant velocity for ten minutes. We assigned individual macrophyte species to life form and identified representative species for each life form. A total of 87 macrophyte taxa were identified. The "emergent" life forms contained the highest number of species, followed by "rooted submerged" life forms. The extensive survey of macrophytes undertaken in September 2008 recorded more species than a survey conducted between 1995 and 1998. This could be due to changes in water physico-chemistry, disturbances due to water drawdown and the long period between surveys, which may have allowed natural colonization by other species. Additionally, differences in the classification systems and taxonomic resolution used in the surveys may account for differences in the number of species recorded. Assemblage composition varied among the arms and was affected by underwater radiation (as measured using a Secchi disk) and fetch. Five non-native species were found. Two of these non-native species (Urochloa subquadripara and Hydrilla verticillata) are of special concern because they have a high frequency of occurrence and occupy large marginal areas of the reservoir. Future surveys should be

Sediment nitrogen cycling rates and microbial abundance along a submerged vegetation gradient in a eutrophic lake.

Science.gov (United States)

Yao, Lu; Chen, Chengrong; Liu, Guihua; Liu, Wenzhi

2018-03-01

Decline of submerged vegetation is one of the most serious ecological problems in eutrophic lakes worldwide. Although restoration of submerged vegetation is widely assumed to enhance ecological functions (e.g., nitrogen removal) and aquatic biodiversity, the evidence for this assumption is very limited. Here, we investigated the spatio-temporal patterns of sediment potential nitrification, unamended denitrification and N 2 O production rates along a vegetation gradient in the Lake Honghu, where submerged vegetation was largely restored by prohibiting net-pen aquaculture. We also used five functional genes as markers to quantify the abundance of sediment nitrifying and denitrifying microorganisms. Results showed that unvegetated sediments supported greater nitrification rates than rhizosphere sediments of perennial or seasonal vegetation. However, the absence of submerged vegetation had no significant effect on denitrification and N 2 O production rates. Additionally, the abundance of functional microorganisms in sediments was not significantly different among vegetation types. Season had a strong effect on both nitrogen cycling processes and microbial abundances. The highest nitrification rates were observed in September, while the highest denitrification rates occurred in December. The temporal variation of sediment nitrification, denitrification and N 2 O production rates could be due to changes in water quality and sediment properties rather than submerged vegetation and microbial abundances. Our findings highlight that vegetation restoration in eutrophic lakes improves water quality but does not enhance sediment nitrogen removal rates and microbial abundances. Therefore, for reducing the N level in eutrophic lakes, major efforts should be made to control nutrients export from terrestrial ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhanced Sorbitol Production under Submerged Fermentation using Lactobacillus plantarum

Directory of Open Access Journals (Sweden)

Khan Nadiya Jan

2017-04-01

Full Text Available Background and Objective: Sorbitol is a non-toxic and slightly hygroscopic compound with different applications. Zymomonas mobiles produces sorbitol from sucrose or mixtures of glucose and fructose (formation is coupled with the dehydrogenation of glucose to glucono-δ- lactone. Recombinant Zymomonas mobilis may produce sorbitol and gluconic acid from glucose and fructose using different divalent metal ions with reduced the ethanol yield andsignificantly increased yield of sorbitol. Current study envisaged to alter the media components, physical process parameters and supplementation of amino acids for enhanced sorbitol production.Material and Methods: Several process variables were evaluated on sorbitol production including carbon sources (glucose, fructose, maltose, sucrose, carbon concentrations (5, 10, 20 and 25 g l-1, nitrogen sources (peptone, tryptone, yeast extract, beef extract and organic nitrogen mix, temperatures (25, 29, 33, 37, 41°C, pH (6, 6.5, 7 , 7.5 ,8, agitation rate (50, 100, 150, 200 rpm and amino acids (cysteine, cystine, tryptophanin batch cultivation ofLactobacillus plantarum NCIM 2912. Shake flask cultivation performed under optimum conditions like temperature 37°C, pH 7.0 and agitation rate of 150 rpm, resulted in enhanced sorbitol production. Comparative study of sorbitol production in solid state fermentation and submerged fermentation was also evaluated.Results and Conclusion: Batch cultivation under submerged conditions further performed in 7.5-l lab scale bioreactor (working volume 3.0-l under optimized conditions resulted in maximum cell biomass of 8.95±0.03 g g-1 and a sorbitol content of 9.78±0.04 g l-1 after 42.0 h of fermentation. Scale up study on bioreactor resulted in maximum sorbitol yield (Yp/x and productivity of 1.11 g g-1 and 0.50 g l-1 h under submerged fermentation, respectively.Conflict of interest: The authors declare no conflict of interest.

A New Detection Method for Submerged Implants: Oral Tattoo.

Science.gov (United States)

Soylu, Emrah; Gönen, Zeynep Burçin; Alkan, Alper

2018-04-01

To evaluate the marking potential of tattoo ink in determining the definitive locations of submerged implants at the time of surgical exposure of the implants. In total, 104 implants in 32 patients were included in this study. After placement of the implants, cover screws were inserted. Overlying mucosa was marked with tattoo ink using a 20 g needle through the center of the cover screw. At the time of surgical exposure the tattoo marks were evaluated relative to visibility. At the time of the surgical exposures, tattoo ink was clearly visible at 91 implants, slightly visible at 8 implants, and not visible at 5 implants. After detection and classification of tattoo ink, the overlying mucosa was gently removed by tissue punch under local anesthesia. The results of this study seemed to indicate that marking the location of implants with tattoos at the time of implant placement can be an inexpensive, easy, healthy, and practical way to identify the location of marked submerged dental implants. © 2016 by the American College of Prosthodontists.

Calibration of submerged multi-sluice gates

Directory of Open Access Journals (Sweden)

Mohamed F. Sauida

2014-09-01

The main objective of this work is to study experimentally and verify empirically the different parameters affecting the discharge through submerged multiple sluice gates (i.e., the expansion ratios, gates operational management, etc.. Using multiple regression analysis of the experimental results, a general equation for discharge coefficient is developed. The results show, that the increase in the expansion ratio and the asymmetric operation of gates, give higher values for the discharge coefficient. The obtained predictions of the discharge coefficient using the developed equations are compared to the experimental data. The present developed equations showed good consistency and high accuracy.

Beach impacts of shore-parallel breakwaters backing offshore submerged ridges, Western Mediterranean Coast of Egypt.

Science.gov (United States)

Iskander, Moheb M; Frihy, Omran E; El Ansary, Ahmed E; El Mooty, Mohamed M Abd; Nagy, Hossam M

2007-12-01

Seven breakwaters were constructed behind offshore submerged ridges to create a safe area for swimming and recreational activities west of Alexandria on the Mediterranean coast of Egypt. Morphodynamic evaluation was based on the modified Perlin and Dean numerical model (ImSedTran-2D) combined with successive shoreline and beach profile surveys conducted periodically between April 2001 and May 2005. Results reveal insignificant morphologic changes behind the detached breakwaters with slight coastline changes at the down and up-drift beaches of the examined breakwaters (+/-10 m). These changes are associated with salient accretion (20-7 0m) in the low-energy leeside of such structures. Concurrent with this sand accretion is the accumulation of a large amount of benthic algae (Sargassum) in the coastal water of the shadow area of these structures, which in turn have adverse effects on swimmers. Practical measures proposed in this study have successfully helped in mitigating such accumulation of algae in the recreation leeside of the breakwaters. The accumulation of Sargassum, together with the virtual insignificant changes in the up-drift and down-drifts of these structures, is a direct response to both coastal processes and the submerged carbonate ridges. Coastal processes encompass reversal of the directions of long-shore sand transport versus shoreline orientation, the small littoral drift rate and sand deficiency of the littoral zone. The beach response to the breakwaters together with the submerged ridges has also been confirmed by applying the ImSedTran-2D model. Results indicate that submerged ridges play a principal role in the evolution of beach morphology along the west coast of Alexandria. Although the study area is exposed to more than 70% wave exposures, the morphodynamic behavior of the beaches indicates that the submerged ridges act in a similar way as an additional natural barrier together with the artificial detached structures.

Genetic potentiality of indigenous rice genotypes from Eastern India with reference to submergence tolerance and deepwater traits

Directory of Open Access Journals (Sweden)

Sayani Goswami

2017-09-01

Full Text Available Submergence tolerance in rice varieties is crucial for maintaining stable yields in low land areas, where recurrence of flooding is a constant phenomenon during monsoon. We have conducted detailed physiological and genotyping studies of 27 rice genotypes and one wild rice relative, popularly grown in low land areas of the two major rice growing states of eastern India, West Bengal and Odisha with a focus on submergence tolerance traits and Sub1 loci. We found that these genotypes show varying degree (50–100% survival rate during post submergence recovery period, and high degree of polymorphism in the Sub1 linked rice microsatellite loci RM219 and RM7175. Detailed allelic diversity study of Sub1A loci suggests that rice varieties IR42, Panibhasha, Khoda and Kalaputia share a common allele that is different from FR13A, Keralasundari, Bhashakalmi, Kumrogore. Two other genotypes Meghi and Khoda shares both alleles of Sub1A loci (present in IR42 and FR13A groups in addition to a new variant. Detailed sequence analysis of the amplified product for the Sub1A loci from these genotypes showed several single nucleotide changes with respect to reference Oryza sativa Sub1A loci (DQ011598. Three rice genotypes (Meghi, Bhashakalmi and Keralasundari showed beneficial properties in relation to induced submergence stress and can be considered as valuable genetic source in context of utilization of natural rice genetic resources in breeding program for submergence tolerance.

Effects of Long-Term Periodic Submergence on Photosynthesis and Growth of Taxodium distichum and Taxodium ascendens Saplings in the Hydro-Fluctuation Zone of the Three Gorges Reservoir of China.

Directory of Open Access Journals (Sweden)

Chaoying Wang

Full Text Available Responses of bald cypress (Taxodium distichum and pond cypress (Taxodium ascendens saplings in photosynthesis and growth to long-term periodic submergence in situ in the hydro-fluctuation zone of the Three Gorges Dam Reservoir (TGDR were studied. Water treatments of periodic deep submergence (DS and moderate submergence (MS in situ were imposed on 2-year-old bald cypress and pond cypress saplings. The effects of periodic submergence on photosynthesis and growth were investigated after 3 years (i.e. 3 cycles compared to a control (i.e. shallow submergence, abbreviated as SS. Results showed that pond cypress had no significant change in net photosynthetic rate (Pn in response to periodic moderate and deep submergence in contrast to a significant decrease in Pn of bald cypress under both submergence treatments, when compared to that of SS. Ratios of Chlorophyll a/b and Chlorophylls/Carotenoid of pond cypress were significantly increased in periodic moderate submergence and deep submergence, while bald cypress showed no significant change. Diameter at breast height (DBH and tree height of both species were significantly reduced along with submergence depth. Relative diameter and height growth rates of the two species were also reduced under deeper submergence. Moreover, bald cypress displayed higher relative diameter growth rate than pond cypress under deep submergence mainly attributed to higher productivity of the larger crown area of bald cypress. When subjected to deep subergence, both species showed significant reduction in primary branch number, while in moderate submergence, bald cypress but not pond cypress showed significant reduction in primary branch number. These results indicate that both bald cypress and pond cypress are suitbale candidates for reforestation in the TGDR region thanks to their submergence tolerance characteristics, but bald cypress can grow better than pond cypress under deep submergence overall.

Surface Intermediate Zone of Submerged Turbulent Buoyant Jet in Current

DEFF Research Database (Denmark)

Chen, H. B.; Larsen, Torben

1995-01-01

This paper deals with the intermediate zone between the jet and plume stages of a submerged buoyant discharge from sea outfall in current. The stability criteria, plume width and height after the intermediate zone and the dilution within the intermediate region have been studied theoretically and...

Heavy metals in water, sediments and submerged macrophytes in ponds around the Dianchi Lake, China.

Science.gov (United States)

Wang, Zhixiu; Yao, Lu; Liu, Guihua; Liu, Wenzhi

2014-09-01

Through retaining runoff and pollutants such as heavy metals from surrounding landscapes, ponds around a lake play an important role in mitigating the impacts of human activities on lake ecosystems. In order to determine the potential for heavy metal accumulation of submerged macrophytes, we investigated the concentrations of 10 heavy metals (i.e., As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in water, sediments, and submerged macrophytes collected from 37 ponds around the Dianchi Lake in China. Our results showed that both water and sediments of these ponds were polluted by Pb. Water and sediments heavy metal concentrations in ponds received urban and agricultural runoff were not significantly higher than those in ponds received forest runoff. This result indicates that a large portion of heavy metals in these ponds may originate from atmospheric deposition and weathering of background soils. Positive relationships were found among heavy metal concentrations in submerged macrophytes, probably due to the coaccumulation of heavy metals. For most heavy metals, no significant relationships were found between submerged macrophytes and their water and sediment environments. The maximum concentrations of Cr, Fe and Ni in Ceratophyllum demersum were 4242, 16,429 and 2662mgkg(-1), respectively. The result suggests that C. demersum is a good candidate species for removing heavy metals from polluted aquatic environments. Copyright © 2014 Elsevier Inc. All rights reserved.

Agenesis of premolar associated with submerged primary molar and a supernumerary premolar: An unusual case report

Directory of Open Access Journals (Sweden)

S. V. S. G. Nirmala

2012-01-01

Full Text Available The combination of submerged primary molar, agenesis of permanent successor with a supernumerary in the same place is very rare. The purpose of this article is to report a case of submerged mandibular left second primary molar with supernumerary tooth in the same region along with agenesis of second premolar in an 11-year-old girl, its possible etiological factors, and a brief discussion on treatment options.

THE INFLUENCE OF SUBMERGED MACROPHYTES ON SEDIMENTARY DIATOM ASSEMBLAGES(1).

Science.gov (United States)

Vermaire, Jesse C; Prairie, Yves T; Gregory-Eaves, Irene

2011-12-01

Submerged macrophytes are a central component of lake ecosystems; however, little is known regarding their long-term response to environmental change. We have examined the potential of diatoms as indicators of past macrophyte biomass. We first sampled periphyton to determine whether habitat was a predictor of diatom assemblage. We then sampled 41 lakes in Quebec, Canada, to evaluate whether whole-lake submerged macrophyte biomass (BiomEpiV) influenced surface sediment diatom assemblages. A multivariate regression tree (MRT) was used to construct a semiquantitative model to reconstruct past macrophyte biomass. We determined that periphytic diatom assemblages on macrophytes were significantly different from those on wood and rocks (ANOSIM R = 0.63, P macrophyte, nutrient-limited lakes (BiomEpiV ≥525 μg · L(-1) ; total phosphorus [TP] macrophyte, nutrient-limited lakes (BiomEpiV macrophytes have a significant influence on diatom community structure and that sedimentary diatom assemblages can be used to infer past macrophyte abundance. © 2011 Phycological Society of America.

Investigation of scour adjacent to submerged geotextiles used for shore protection

Energy Technology Data Exchange (ETDEWEB)

Gorton, Alicia M.; Herrington, Thomas O.; Smith, Ernest R.

2018-01-03

This study presents the results of an experimental investigation of morphology change in the vicinity of submerged geotextiles placed within the surf zone. The study was motivated by the emerging use of submerged geotextile tubes for shore protection, shoreline stabilization, and surf amenity enhancement and the need to understand the mechanisms responsible for scour in the vicinity of these structures to preserve their structural integrity and reduce their structural failure. A movable bed physical model experiment was conducted at the U.S. Army Engineer Research and Development Center’s Large-scale Sediment Transport Facility (LSTF) to develop empirical formulations to predict the mean scour depth adjacent to geotextiles under oblique wave-breaking conditions as a function of the maximum Keulegan-Carpenter, Shields, and Reynolds numbers. The observed scour in the vicinity of the geotextiles was also compared to a previous study of scour in the vicinity of submerged cylinders. Formulations developed by Cataño-Lopera and García (2006) relating the Keulegan-Carpenter, Shields, and Reynolds numbers to the scour depth were used to predict the scour observed during the LSTF experiment. Results show that the formulations of Cataño-Lopera and García (2006) over-predict the observed scour when calculated using the maximum Keulegan-Carpenter, Shields, and Reynolds numbers. New, modified expressions of Cataño-Lopera and García (2006) were developed for use in oblique random wave fields.

Mathematical investigation of tsunami-like long waves interaction with submerge dike of different thickness

Science.gov (United States)

Zhiltsov, Konstantin; Kostyushin, Kirill; Kagenov, Anuar; Tyryshkin, Ilya

2017-11-01

This paper presents a mathematical investigation of the interaction of a long tsunami-type wave with a submerge dike. The calculations were performed by using the freeware package OpenFOAM. Unsteady two-dimensional Navier-Stokes equations were used for mathematical modeling of incompressible two-phase medium. The Volume of Fluid (VOF) method is used to capture the free surface of a liquid. The effects caused by long wave of defined amplitude motion through a submerged dike of varying thickness were discussed in detail. Numerical results show that after wave passing through the barrier, multiple vortex structures were formed behind. Intensity of vortex depended on the size of the barrier. The effectiveness of the submerge barrier was estimated by evaluating the wave reflection and transmission coefficients using the energy integral method. Then, the curves of the dependences of the reflection and transmission coefficients were obtained for the interaction of waves with the dike. Finally, it was confirmed that the energy of the wave could be reduced by more than 50% when it passed through the barrier.

ASPECTS OF BIODETERIORATION OF LAPIDEOUS SUBMERGED ARTEFACTS: 3D METHODOLOGIES APPLICATION

Directory of Open Access Journals (Sweden)

S. Ricci

2015-04-01

Full Text Available Submerged stone archaeological artefacts are bioeroded by endolithic microbiota (cyanobacteria, algae and fungi and macroborers (Porifera, Bivalvia and Sipuncula. Optical microscope and SEM observations permit to analyse the bioerosion traces and to identify bioeroders. Data obtained with these techniques cannot be used to estimate volumes of material bioeroded. This aspect require the need to collect three-dimensional, close-range data from artefact. In this work we illustrate two 3D imaging techniques used to study bioerosion phenomena of underwater Cultural Heritage. In particular Digital Video Microscope permit the elaboration of 3D images, which are widely employed for close-range acquisitions. Underwater Laser Scanner documents the in situ degradation of submerged artefacts. This research aims to sensitize specialist figures in the study 3D offering a starting point for future collaborations that could lead to interesting results.

Application of gas shielded arc welding and submerged arc welding for fabrication of nuclear reactor vessels

International Nuclear Information System (INIS)

Gehani, M.L.; Rodrigues, W.D.

1976-01-01

The remarkable progress made in the development of knowhow and expertise in the manufacture of equipment for nuclear power plants in India is outlined. Some of the specific advances made in the application of higher efficiency weld processes for fabrication of nuclear reactor vessels and the higher level of quality attained are discussed in detail. Modifications and developments in submerged arc, gas tungsten arc and gas metal arc processes for welding of Calandria which have been a highly challenging and rewarding experience are discussed. Future scope for making the gas metal arc process more economical by using various gas-mixes like Agron + Oxygen, Argon + Carbon Dioxide, Argon + Nitrogen (for Copper Alloys) etc., in various proportions are outlined. Quality and dimensional control exercised in these jobs of high precision are highlighted. (K.B.)

Sorghum bagasse as substrate for cellulase production by submerged and solid-state cultures of Trichoderma

Directory of Open Access Journals (Sweden)

Teodor Vintilă

2014-05-01

Full Text Available Sweet sorghum bagasse was used as cellulosic substrate in submerged and solid-state cultures of Trichoderma for cellulase production. Submerged liquid cultures (SLC were obtained by inoculation of Mandels media containing 1% cellulose with spores suspension of Trichoderma. Solid-state cultures (SSC were carried out in Erlenmayer flasks, where the substrate was distributed 1 cm layers. Comparing the yields of cellulases produced by Trichoderma strains in the systems applied in this study, using as substrate sorghum bagasse, we found the solid-state cultures as the system to produce the highest cellulase yields. The local strain of T. viride CMIT3.5. express high productivity in SSC system in laboratory conditions. The cellulolytic enzymes have maximum activity at 50oC, pH 4,8. The results recommend solid-state cultures of Trichoderma on sorghum bagasse as systems for producing cellulolytic products with higher activity than submerged cultures of Trichoderma on the same substrate.

Submerged membrane distillation for seawater desalination

KAUST Repository

Francis, Lijo; Ghaffour, NorEddine; Alsaadi, Ahmad Salem; Amy, Gary L.

2014-01-01

A submerged membrane distillation (SMD) process for fresh water production from Red Sea water using commercially available hollow fiber membranes has been successfully employed and compared with the conventional direct contact membrane distillation (DCMD) process. The hollow fiber membranes have been characterized for its morphology using field effect scanning electron microscope. In SMD process, a bunch of hollow fiber membranes are glued together at both ends to get a simplified open membrane module assembly submerged into the coolant tank equipped with a mechanical stirrer. Hot feed stream is allowed to pass through the lumen side of the membrane using a feed pump. Continuous stirring at the coolant side will reduce the temperature and concentration polarization. During the conventional DCMD process, using feed-coolant streams with co-current and counter-current flows has been tested and the results are compared in this study. In SMD process, a water vapor flux of 10.2 kg m-2 h-1 is achieved when using a feed inlet temperature of 80°C and coolant temperature of 20°C. Under the same conditions, during conventional DCMD process, a water vapor flux of 11.6 and 10.1 kg m-2 h-1 were observed during counter-current and co-current flow streams, respectively. Results show that the water production in the SMD process is comparable with the conventional DCMD process, while the feed-coolant flow streams are in the co-current direction. During conventional DCMD operation, a 15% increase in the water production is observed when feed-coolant streams are in the counter-current direction compared to the co-current direction. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.

Workshop on ROVs and deep submergence

Science.gov (United States)

The deep-submergence community has an opportunity on March 6 to participate in a unique teleconferencing demonstration of a state-of-the-art, remotely operated underwater research vehicle known as the Jason-Medea System. Jason-Medea has been developed over the past decade by scientists, engineers, and technicians at the Deep Submergence Laboratory at Woods Hole Oceanographic Institution. The U.S. Navy, the Office of the Chief of Naval Research, and the National Science Foundation are sponsoring the workshop to explore the roles that modern computational, communications, and robotics technologies can play in deep-sea oceanographic research.Through the cooperation of Electronic Data Systems, Inc., the Jason Foundation, and Turner Broadcasting System, Inc., 2-1/2 hours of air time will be available from 3:00 to 5:30 PM EST on March 6. Twenty-seven satellite downlink sites will link one operating research vessel and the land-based operation with workshop participants in the United States, Canada, the United Kingdom, and Bermuda. The research ship Laney Chouest will be in the midst of a 3-week educational/research program in the Sea of Cortez, between Baja California and mainland Mexico. This effort is focused on active hydrothermal vents driven by heat flow from the volcanically active East Pacific Rise, which underlies the sediment-covered Guaymas Basin. The project combines into a single-operation, newly-developed robotic systems, state-of-the-art mapping and sampling tools, fiber-optic data transmission from the seafloor, instantaneous satellite communication from ship to shore, and a sophisticated array of computational and telecommunications networks. During the workshop, land-based scientists will observe and participate directly with their seagoing colleagues as they conduct seafloor research.

Submerged membrane distillation for seawater desalination

KAUST Repository

Francis, Lijo

2014-08-11

A submerged membrane distillation (SMD) process for fresh water production from Red Sea water using commercially available hollow fiber membranes has been successfully employed and compared with the conventional direct contact membrane distillation (DCMD) process. The hollow fiber membranes have been characterized for its morphology using field effect scanning electron microscope. In SMD process, a bunch of hollow fiber membranes are glued together at both ends to get a simplified open membrane module assembly submerged into the coolant tank equipped with a mechanical stirrer. Hot feed stream is allowed to pass through the lumen side of the membrane using a feed pump. Continuous stirring at the coolant side will reduce the temperature and concentration polarization. During the conventional DCMD process, using feed-coolant streams with co-current and counter-current flows has been tested and the results are compared in this study. In SMD process, a water vapor flux of 10.2 kg m-2 h-1 is achieved when using a feed inlet temperature of 80°C and coolant temperature of 20°C. Under the same conditions, during conventional DCMD process, a water vapor flux of 11.6 and 10.1 kg m-2 h-1 were observed during counter-current and co-current flow streams, respectively. Results show that the water production in the SMD process is comparable with the conventional DCMD process, while the feed-coolant flow streams are in the co-current direction. During conventional DCMD operation, a 15% increase in the water production is observed when feed-coolant streams are in the counter-current direction compared to the co-current direction. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.

Effects of substrate concentration, specific surface area and hydraulic loading on the treatment efficiency in a submerged biological filter. Sesshoku bakkiho no shori koritsu ni taisuru kishitsu nodo, hihyo menseki oyobi suiryo fuka no eikyo

Energy Technology Data Exchange (ETDEWEB)

Iyo, T; Ono, S; Yoshino, T [Kitasato University, Kanagawa (Japan). School of Hygienic Science

1991-06-10

Effects of substrate concentration, specific surface area, and hydraulic loading, which are major factors influencing treatment efficiency in a submerged biological filter, were analyzed through the test with a special apparatus. In the test, the wall of the submerged biological filter was regarded as the contact material, and the specific surface area was changed by adjusting the sectional form of the filter. Using specimens from actual plant reservoirs, treatment efficiency for each case of three kinds of substrate concentration and hydraulic loading was measured. BOD removal rate was lower with smaller specific surface area. It was conspicuous particularly with higher BOD concentration in influent water. After the multiple regression analysis of the test results, the multiple regression equation to estimate BOD residual rate from three variates such as BOD concentration, specific surface area, and hydraulic loading was obtained. When 200mg l as BOD concentration and 50m{sup 2} m{sup {minus}3} as specific surface area were applied in this equation, the result almost agreed with the tendency obtained from data of actual plants. 6 refs., 4 figs., 1 tab.

GigaUnit Transplant System: A New Mechanical Tool for Transplanting Submerged Aquatic Vegetation

National Research Council Canada - National Science Library

Shafer, Deborah J

2008-01-01

Submerged aquatic vegetation (SAV) performs many important ecosystem functions, including wave attenuation and sediment stabilization, water quality improvement, primary production, food web support for secondary consumers...

Aerobic and anaerobic ethanol production by Mucor circinelloides during submerged growth

DEFF Research Database (Denmark)

Lübbehüsen, Tina Louise; Nielsen, Jens; Mcintyre, Mhairi

2004-01-01

The dimorphic organism Mucor circinelloides is currently being investigated as a potential host for heterologous protein production. The production of ethanol on pentose and hexose sugars was studied in submerged batch cultivations to further the general knowledge of Mucor physiology, with a view...

Sludge mobilization with submerged nozzles in horizontal cylindrical tanks

International Nuclear Information System (INIS)

Hylton, T.D.; Cummins, R.L.; Youngblood, E.L.; Perona, J.J.

1995-10-01

The Melton Valley Storage Tanks (MVSTs) and the evaporator service tanks at the Oak Ridge National Laboratory (ORNL) are used for the collection and storage of liquid low-level waste (LLLW). Wastes collected in these tanks are typically acidic when generated and are neutralized with sodium hydroxide to protect the tanks from corrosion; however, the high pH of the solution causes the formation of insoluble compounds that precipitate. These precipitates formed a sludge layer approximately 0.6 to 1.2 m (2 to 4 ft) deep in the bottom of the tanks. The sludge in the MVSTs and the evaporator service tanks will eventually need to be removed from the tanks and treated for final disposal or transferred to another storage facility. The primary options for removing the sludge include single-point sluicing, use of a floating pump, robotic sluicing, and submerged-nozzle sluicing. The objectives of this study were to (1) evaluate the feasibility of submerged-nozzle sluicing in horizontal cylindrical tanks and (2) obtain experimental data to validate the TEMPEST (time-dependent, energy, momentun, pressure, equation solution in three dimensions) computer code

The effect of atmospheric carbon dioxide elevation on plant growth in freshwater ecosystems

NARCIS (Netherlands)

Schippers, P.; Vermaat, J.; Klein, de J.J.M.; Mooij, W.M.

2004-01-01

The authors developed a dynamic model to investigate the effect of atmospheric carbon dioxide (CO2) increase on plant growth in freshwater ecosystems. Steady-state simulations were performed to analyze the response of phytoplankton and submerged macrophytes to atmospheric CO2 elevation from 350 to

Structure of strongly underexpanded gas jets submerged in liquids – Application to the wastage of tubes by aggressive jets

Energy Technology Data Exchange (ETDEWEB)

Roger, Francis, E-mail: roger@ensma.fr [Institut PPRIME, Département Fluides, Thermique, Combustion CNRS ENSMA Université de Poitiers UPR 3346, ENSMA BP 109, 86960 Futuroscope Cedex (France); Carreau, Jean-Louis; Gbahoué, Laurent; Hobbes, Philippe [Institut PPRIME, Département Fluides, Thermique, Combustion CNRS ENSMA Université de Poitiers UPR 3346, ENSMA BP 109, 86960 Futuroscope Cedex (France); Allou, Alexandre; Beauchamp, François [CEA, DEN, Cadarache, DTN/STPA/LTRS, 13108 Saint-Paul lez, Durance Cedex (France)

2014-07-01

Highlights: • Underexpanded gas jets submerged in liquids behave similarly to homogeneous gas jets. • The counter rotating vortex pairs of jet produce discrete imprints on the targets. • The shape of hollows made on the targets is explained by the jet structure. • The erosion–corrosion phenomenon well explains the wastage of exchange tubes. - Abstract: Strongly underexpanded gas jets submerged in a liquid at rest behave similarly to underexpanded homogeneous gas jets. The existence of the Taylor-Görtler vortices around the inner zone of the gas jets is demonstrated in free gas jets submerged in water by means of optical probe. In the near field, the same phenomenon produces discrete imprints, approximately distributed in a circle, when underexpanded nitrogen jet submerged in liquid sodium hydroxide and underexpanded water vapour jet submerged in liquid sodium impact onto AU{sub 4}G-T{sub 4} and Incoloy 800{sup ®} alloy targets respectively. For a jet-target couple, the volume of the hollow is satisfactorily related to the strain energy density of the material and the kinetic energy of the gas jet. However, the comparison between volumes of hollows produced by both jets also indicates strong corrosive action of the medium on targets. This allows better understanding of the mechanism of wastage of tubes employed in steam generators integrated in liquid metal fast breeder reactors.

Global sensitivity analysis of a filtration model for submerged anaerobic membrane bioreactors (AnMBR).

Science.gov (United States)

Robles, A; Ruano, M V; Ribes, J; Seco, A; Ferrer, J

2014-04-01

The results of a global sensitivity analysis of a filtration model for submerged anaerobic MBRs (AnMBRs) are assessed in this paper. This study aimed to (1) identify the less- (or non-) influential factors of the model in order to facilitate model calibration and (2) validate the modelling approach (i.e. to determine the need for each of the proposed factors to be included in the model). The sensitivity analysis was conducted using a revised version of the Morris screening method. The dynamic simulations were conducted using long-term data obtained from an AnMBR plant fitted with industrial-scale hollow-fibre membranes. Of the 14 factors in the model, six were identified as influential, i.e. those calibrated using off-line protocols. A dynamic calibration (based on optimisation algorithms) of these influential factors was conducted. The resulting estimated model factors accurately predicted membrane performance. Copyright © 2014 Elsevier Ltd. All rights reserved.

ALPHA-AMYLASE PRODUCTION FROM Aspergillus oryzae M BY SUBMERGED FERMENTATION

Directory of Open Access Journals (Sweden)

Suleimenova

2016-08-01

Full Text Available The main goal of present study was implementation of the Aspergillus oryzae M strain improved technology using earlier developed method of microorganism selection. 8 pure strains of Aspergillus fungi were screened for the production of extra cellular alpha-amylase using agar medium with starch as a substrate and incubated for 72h at 30 ºС. Zone of clearance was observed for screening of the amylolytic fungi (in mm. Aspergillus oryzae M has demonstrated the highest zone of clearance. Aspergillus oryzae M was cultivated for 42 days in submerged conditions of growth using new method of fungal cultivation. This method based on immobilizing enzymes producers on solid career in submerged conditions of growth gives the way to improve quality of filtrates, which remain clear, does not require additional filtering and easily separated from the mycelium. Moreover, it allows to prolong the process of fungal cultivation and to maintain high enzymatic activity for a long period of time. Presented method allowed increasing alpha-amylase production from 321 U/ml (before immobilization to 502 U/ml (after immobilization.

Modeling Refuge Effect of Submerged Macrophytes in Lake System.

Science.gov (United States)

Lv, Dongyu; Fan, Meng; Kang, Yun; Blanco, Krystal

2016-04-01

This paper considers a significant problem in biological control of algae issue in ecological environment. A four-dimensional dynamic model is carefully formulated to characterize the interactions among phytoplankton, submerged macrophyte, zooplankton, and general fish class in a lake ecosystem. The predation relationship is modeled by Beddington-DeAngelis functional responses derived from the classical Holling time budget arguments. Qualitative analyses of the global dynamics show that the system can generate very rich dynamics with potentially 10 different equilibria and several bistable scenarios. We perform analysis on the existence and local stability of equilibria and explore the refuge effect of macrophyte on the zooplankton with numerical simulations on aquatic ecosystems. We also discuss effective methods of biological control used to restrain the increase of phytoplankton. Our study shows the proposed model could have rich and complex dynamics including but not limited to bistable and chaotic phenomenon. Numerical simulation results demonstrate that both the refuge constant and the density of the macrophytes are two key factors where refuge effects take place. In addition, the intraspecific competition between the macrophyte and the phytoplankton can also affect the macrophyte's refuge effect. Our analytical and simulation results suggest that macrophytes provide structure and shelter against predation for zooplankton such that it could restore the zooplankton population, and that planting macrophyte properly might achieve the purpose of controlling algae growth.

The effect of atmospheric carbon dioxide elevation on plant growth in freshwater ecosystems

NARCIS (Netherlands)

Schippers, P.; Vermaat, J.E.; de Klein, J.; Mooij, W.M.

2004-01-01

We developed a dynamic model to investigate the effect of atmospheric carbon dioxide (CO2) increase on plant growth in freshwater ecosystems. Steady-state simulations were performed to analyze the response of phytoplankton and submerged macrophytes to atmospheric CO2 elevation from 350 to 700 ppm.

Akkumulation von L-Malat und D-Lactat in Arabidopsis thaliana und Laccase/HBT-vermittelte Delignifizierung von Spartina alterniflora und Phragmites australis

OpenAIRE

Heil, Alexander

2016-01-01

The current work contains two projects "Accumulation of L-malate and D-lactate in Arabidopsis thaliana" (A) "Laccase/HBT mediated delignification of Spartina alterniflora and Phragmites australis" (B). In project A, L-malate and D-lactate accumulated in A. thaliana plants. The accumulation of L-malate is carried out by modification of the plant metabolism with the enzymes PEPC, MDH and the tonoplast dicarboxylate transporter (TDT). Gene pepci2 (Hydrilla verticillata), mdh5 (Zea mays) and tdt ...

Emergent and floating-leaved macrophytes as refuge for zooplankton in a eutrophic temperate lake without submerged vegetation

DEFF Research Database (Denmark)

Cazzanelli, Matteo; Perlt, Trine Warming; Christoffersen, Kirsten Seestern

2008-01-01

Several studies have shown that submerged macrophytes provide a refuge for zooplankton against fish predation, whereas the role of emergent and floating-leaved species, which are often dominant in eutrophic turbid lakes, is far less investigated. Zooplankton density in open water and amongst....... As a consequence, especially in turbid lakes, the ecological role of these functional types of vegetation, and not merely that of submerged macrophyte species, should be taken into consideration....

Design procedure for sizing a submerged-bed scrubber for airborne particulate removal

International Nuclear Information System (INIS)

Ruecker, C.M.; Scott, P.A.

1987-04-01

Performance correlations to design and operate the submerged bed scrubber were developed for various applications. Structural design procedure outlined in this report focuses on off-gas scrubbing for HLW vitrification applications; however, the method is appropriate for other applications

Production of destruxins from Metarhizium spp. fungi in artificial medium and in endophytically colonized cowpea plants.

Directory of Open Access Journals (Sweden)

Patrícia S Golo

Full Text Available Destruxins (DTXs are cyclic depsipeptides produced by many Metarhizium isolates that have long been assumed to contribute to virulence of these entomopathogenic fungi. We evaluated the virulence of 20 Metarhizium isolates against insect larvae and measured the concentration of DTXs A, B, and E produced by these same isolates in submerged (shaken cultures. Eight of the isolates (ARSEF 324, 724, 760, 1448, 1882, 1883, 3479, and 3918 did not produce DTXs A, B, or E during the five days of submerged culture. DTXs were first detected in culture medium at 2-3 days in submerged culture. Galleria mellonella and Tenebrio molitor showed considerable variation in their susceptibility to the Metarhizium isolates. The concentration of DTXs produced in vitro did not correlate with percent or speed of insect kill. We established endophytic associations of M. robertsii and M. acridum isolates in Vigna unguiculata (cowpeas and Cucumis sativus (cucumber plants. DTXs were detected in cowpeas colonized by M. robertsii ARSEF 2575 12 days after fungal inoculation, but DTXs were not detected in cucumber. This is the first instance of DTXs detected in plants endophytically colonized by M. robertsii. This finding has implications for new approaches to fungus-based biological control of pest arthropods.

A submerged ceramic membrane reactor for the p-nitrophenol hydrogenation over nano-sized nickel catalysts.

Science.gov (United States)

Chen, R Z; Sun, H L; Xing, W H; Jin, W Q; Xu, N P

2009-02-01

The catalytic hydrogenation of p-nitrophenol to p-aminophenol over nano-sized nickel catalysts was carried out in a submerged ceramic membrane reactor. It has been demonstrated that the submerged ceramic membrane reactor is more suitable for the p-nitrophenol hydrogenation over nano-sized nickel catalysts compared with the side-stream ceramic membrane reactor, and the membrane module configuration has a great influence on the reaction rate of p-nitrophenol hydrogenation and the membrane treating capacity. The deactivation of nano-sized nickel is mainly caused by the adsorption of impurity on the surface of nickel and the increase of oxidation degree of nickel.

Response of soil physico-chemical properties to restoration approaches and submergence in the water level fluctuation zone of the Danjiangkou Reservoir, China.

Science.gov (United States)

Shu, Xiao; Zhang, KeRong; Zhang, QuanFa; Wang, WeiBo

2017-11-01

With the completion of the Danjiangkou Dam, the impoundment and drainage of dams can significantly alter shorelines, hydrological regime, and sediment and can result in the loss of soil and original riparian vegetation. Revegetation may affect soil properties and have broad important implications both for ecological services and soil recovery. In this work, we investigated the soil properties under different restoration approaches, and before and after submergence in the water level fluctuation zone (WLFZ) of the Danjiangkou Reservoir. Soil physical (bulk density and soil moisture), chemical (pH, soil organic carbon, nitrogen, phosphorus and potassium contents), and heavy metals were determined. This study reported that restoration approaches have impacts on soil moisture, pH, N, soil organic carbon, P, K and heavy metals in the WLFZ of the Danjiangkou Reservoir. Our results indicated that different restoration approaches could increase the soil moisture while decrease soil pH. Higher soil organic carbon in propagule banks transplantation (PBT) and shrubs restoration (SR) indicate that PBT and SR may provide soil organic matter more quickly than trees restoration (TR). SR and TR could significantly improve the soil total P and available P. PBT and SR could improve the soil total K and available K. SR and TR could significantly promote Cu and Zn adsorption, and Pb and Fe release by plant. Submergence could significantly affect the soil pH, NO 3 － -N, NH 4 ＋ -N, total P and available P. Submergence could promote NO 3 － -N and available P adsorption, and NH 4 ＋ -N and total P release by soil. The soil quality index (SQI) values implied that TR and PBT greatly improved soil quality. The present study suggests that PBT and TR could be effective for soil restoration in WLFZ of the Danjiangkou Reservoir. Copyright © 2017 Elsevier Inc. All rights reserved.

Corrosion monitoring for underground and submerged concrete structures - examples and interpretation issues

NARCIS (Netherlands)

Polder, R.B.; Peelen, W.H.A.; Leegwater, G.

2008-01-01

Since about 1980 Corrosion Monitoring Systems have been used in many concrete structures in aggressive environmentworldwide. While these systemswork properly in aboveground environment, some questions have arisen for submerged conditions, e.g. the outer sides of tunnels, piers in seawater or

Bioconversion and enzymatic activities of neurospora sitophila grown under solid state and submerged fermentation on Sago Hamps

International Nuclear Information System (INIS)

Shojaosadati, S. A.; Vikineswary, S.; Looi, C. C.

2000-01-01

N.Sitophila was grown under controlled conditions of solid state and submerged fermentation on Sago Hampas. The optimum conditions of protein enrichment previously established for sugar beet pulp was used for this study. Under this condition the protein content of Sago Hampas under solid state increased from 1.4 to 14.45% (W/W) whereas for Sago Hampas and Sago starch, the protein content under submerged condition increased from 1.4% (W/W) and 0.7% (W/W) to 18.56% (W/W) and 43/16% (W/W) based on dry weight of product respectively. The cellulase, a-amylase and glucoamylase activities of N.Sitophila under solid state condition on Sago Hampas were, 9.0, 0.6 and 11.8 U/g of wet fermented solid respectively. the enzymatic activities were also measured under submerged fermentation using both Sago Hampas and Sago starch as substrate

Aerosol Scrubbing Performance Test for Self-Priming Scrubbing Nozzle Submerged in Water Pool

Energy Technology Data Exchange (ETDEWEB)

Lee, Doo Yong; Jung, Woo Young; Lee, Hyun Chul; Lee, Jong Chan; Kim, Gyu Tae; Song, Yong Jae [FNC Technology Co., Yongin (Korea, Republic of)

2016-10-15

A scrubbing nozzle is one of the key components for a wet scrubber process based Containment Filtered Venting System (CFVS). As a part of a development of Korean CFVS, a self-priming scrubbing nozzle shown in Fig. 1 has been developed based on the well-known venturi scrubber concept. The thermal-hydraulic performances such as the pressure drop across the nozzle, water suction behavior and droplet generation inside throat have been tested in the non-submerged condition as well as submerged condition. The self-priming scrubbing nozzle used for the wet scrubber based CFVS has been developed, which is submerged in the water pool. When there is gas flow at the inlet of the nozzle, the pool water is passively sucked from the water suction slit. The fine droplets generated inside the throat capture the aerosol particles and is discharged into the water pool. In the water pool, the pool scrubbing happens. The aerosol scrubbing performance tests for the developed self-priming scrubbing nozzle has been conducted under the operational conditions such as different aerosol sizes, different carrier gas steam fractions, different, different pool water level and nozzle inlet pressure. The major findings are as follows. (1) Aerosol scrubbing efficiency increases with the increase of the aerosol size. (2) Aerosol scrubbing efficiency increases with the increase of the carrier gas steam fraction. (3) Aerosol scrubbing.

Aerosol Scrubbing Performance Test for Self-Priming Scrubbing Nozzle Submerged in Water Pool

International Nuclear Information System (INIS)

Lee, Doo Yong; Jung, Woo Young; Lee, Hyun Chul; Lee, Jong Chan; Kim, Gyu Tae; Song, Yong Jae

2016-01-01

A scrubbing nozzle is one of the key components for a wet scrubber process based Containment Filtered Venting System (CFVS). As a part of a development of Korean CFVS, a self-priming scrubbing nozzle shown in Fig. 1 has been developed based on the well-known venturi scrubber concept. The thermal-hydraulic performances such as the pressure drop across the nozzle, water suction behavior and droplet generation inside throat have been tested in the non-submerged condition as well as submerged condition. The self-priming scrubbing nozzle used for the wet scrubber based CFVS has been developed, which is submerged in the water pool. When there is gas flow at the inlet of the nozzle, the pool water is passively sucked from the water suction slit. The fine droplets generated inside the throat capture the aerosol particles and is discharged into the water pool. In the water pool, the pool scrubbing happens. The aerosol scrubbing performance tests for the developed self-priming scrubbing nozzle has been conducted under the operational conditions such as different aerosol sizes, different carrier gas steam fractions, different, different pool water level and nozzle inlet pressure. The major findings are as follows. (1) Aerosol scrubbing efficiency increases with the increase of the aerosol size. (2) Aerosol scrubbing efficiency increases with the increase of the carrier gas steam fraction. (3) Aerosol scrubbing

Large-Scale Submerged Aquatic Vegetation Restoration in Chesapeake Bay: Status Report, 2003-2006

National Research Council Canada - National Science Library

Shafer, Deborah J; Bergstrom, Peter

2008-01-01

In 2003, the U.S. Army Engineer Research and Development Center (ERDC) and the National Oceanic and Atmospheric Administration Chesapeake Bay Office began a comprehensive research effort to restore submerged aquatic vegetation (SAV...

Investigating the molecular basis for heterophylly in the aquatic plant Potamogeton octandrus (Potamogetonaceae with comparative transcriptomics

Directory of Open Access Journals (Sweden)

Dingxuan He

2018-02-01

Full Text Available Many plant species exhibit different leaf morphologies within a single plant, or heterophylly. The molecular mechanisms regulating this phenomenon, however, have remained elusive. In this study, the transcriptomes of submerged and floating leaves of an aquatic heterophyllous plant, Potamogeton octandrus Poir, at different stages of development, were sequenced using high-throughput sequencing (RNA-Seq, in order to aid gene discovery and functional studies of genes involved in heterophylly. A total of 81,103 unigenes were identified in submerged and floating leaves and 6,822 differentially expressed genes (DEGs were identified by comparing samples at differing time points of development. KEGG pathway enrichment analysis categorized these unigenes into 128 pathways. A total of 24,025 differentially expressed genes were involved in carbon metabolic pathways, biosynthesis of amino acids, ribosomal processes, and plant-pathogen interactions. In particular, KEGG pathway enrichment analysis categorized a total of 70 DEGs into plant hormone signal transduction pathways. The high-throughput transcriptomic results presented here highlight the potential for understanding the molecular mechanisms underlying heterophylly, which is still poorly understood. Further, these data provide a framework to better understand heterophyllous leaf development in P. octandrus via targeted studies utilizing gene cloning and functional analyses.

Final Environmental Assessment Implementation of the Integrated Natural Resources Management Plan for Avon Park Air Force Range Florida

Science.gov (United States)

2004-01-01

divine nightshade (Solanum nigrescens) Coast sandspur (Cenchrus incertus) Three plants — tropical soda apple (Solanum viarum), cogon grass ( Imperata ...consequence on the APAFR ecosystem. However in the last 5 years, there has been an increase in the number of sites where cogon grass ( Imperata ...verticillata Hydrilla Hymenachne amplexicaulis West In mdian arsh grass Imperata cylindrica Cogon grass Lantana camara Lantana Ligustrum sinense Chinese

The structuring role of submerged macrophytes in a large subtropical shallow lake

NARCIS (Netherlands)

Finkler Ferreira, Tiago; Crossetti, Luciane O.; Motta Marques, David M.L.; Cardoso, Luciana; Fragoso, Carlos Ruberto; Nes, van Egbert H.

2018-01-01

It is well known that submerged macrophytes exert positive feedback effects that enhance the water transparency, stabilizing the clear-water state in shallow temperate lakes. However, the structuring effect of macrophytes on the food web of subtropical and tropical ecosystems is still poorly

Submerged Humid Tropical Karst Landforms Observed By High-Resolution Multibeam Survey in Nagura Bay, Ishigaki Island, Southwestern Japan

Science.gov (United States)

Kan, H.; Urata, K.; Nagao, M.; Hori, N.; Fujita, K.; Yokoyama, Y.; Nakashima, Y.; Ohashi, T.; Goto, K.; Suzuki, A.

2014-12-01

Submerged tropical karst features were discovered in Nagura Bay on Ishigaki Island in the South Ryukyu Islands, Japan. This is the first description of submerged humid tropical karst using multibeam bathymetry. We conducted a broadband multibeam survey in the central area of Nagura Bay (1.85 × 2.7 km) and visualized the high-resolution bathymetric results with a grid size of 1 m over a depth range of 1.6-58.5 m. Various types of humid tropical karst landforms were found to coexist within the bay, including fluviokarst, doline karst, cockpit karst, polygonal karst, uvalas, and mega-dolines. We assume that Nagura Bay was a large karst basin in which older limestone remained submerged, thus preventing corrosion and the accumulation of reef sediments during periods of submersion, whereas the limestone outcropping on land was corroded during multiple interglacial and glacial periods. Based on our bathymetric result together with aerial photographs of the coastal area, we conclude that the submerged karst landscape has likely developed throughout the whole of Nagura Bay, covering an area of ~6 × 5 km. Accordingly, this area hosts the largest submerged karst in Japan. We also observed abundant coral communities during our SCUBA observations. The present marine conditions of Nagura Bay are characterized by low energy (calm sea) and low irradiance owing to the terrestrial influence. Such conditions have been emphasized by the presence of large undulating landforms, which cause decreases in wave intensity and irradiance with depth. These characteristics have acted to establish unique conditions compared to other coral reef areas in the Ryukyu Islands. It may play an important role in supporting the regional coral reef ecosystem.

Ultrasound imaging measurement of submerged topography in the muddy water physical model

International Nuclear Information System (INIS)

Xiao, Xiongwu; Guo, Bingxuan; Li, Deren; Zhang, Peng; Zang, Yu-fu; Zou, Xianjian; Liu, Jian-chen

2015-01-01

The real-time, accurate measurement of submerged topography is vital for the analysis of riverbed erosion and deposition. This paper describes a novel method of measuring submerged topography in the B-scan image obtained using an ultrasound imaging device. Results show the distribution of gray values in the image has a process of mutation. This mutation process can be used to adaptively track the topographic lines between riverbed and water, based on the continuity of topography in the horizontal direction. The extracted topographic lines, of one pixel width, are processed by a wavelet filtering method. Compared with the actual topography, the measurement accuracy is within 1 mm. It is suitable for the real-time measurement and analysis of all current model topographies with the advantage of good self-adaptation. In particular, it is visible and intuitive for muddy water in the movable-bed model experiment. (paper)

Mass development of monospecific submerged macrophyte vegetation after the restoration of shallow lakes: Roles of light, sediment nutrient levels, and propagule density

NARCIS (Netherlands)

Verhofstad, M.J.J.M.; Alirangues Núñez, M. M.; Reichman, E. P.; van Donk, E.; Lamers, L. P.M.; Bakker, E. S.

2017-01-01

After restoration, eutrophicated shallow freshwaters may show mass development of only one or two submerged macrophyte species, lowering biodiversity and hampering recreation. It is unclear which environmental factors govern this high percentage of the volume inhabited (PVI2) by submerged

Sinopsis sobre las Hydrocharitaceae de Colombia

Directory of Open Access Journals (Sweden)

Schmidt Mumm Udo

1996-06-01

Full Text Available The aquatic family Hydrocharitaceae is actually represented in Colombia by seven genera and seven species (Egeria densa, Apalanthe granatensis, Halophila decipiens, Hydrilla verticillata, Limnobium laevigatum, Thalassia testudinum, Vallisneria americana. A first record of Hydrilla verticillata growing spontaneously in outside conditions is made for this geographical area. A key to genera is presented, with each species briefly commented and illustrated.En Colombia la familia de plantas acuáticas Hydrocharitaceae se encuentra representada por siete géneros y siete especies (Egeria densa, Apalanthe granatensis, Halophila decipiens, Hydrilla verticillata, Limnabium laevigatum, Thalassia testudinum, Vallisneria americana. Para el país se registra por primera vez a Hydrilla verticillata. Adicionalmente se presenta una clave para los géneros, con las especies brevemente comentadas e ilustradas.

Bistatic scattering from submerged unexploded ordnance lying on a sediment.

Science.gov (United States)

Bucaro, J A; Simpson, H; Kraus, L; Dragonette, L R; Yoder, T; Houston, B H

2009-11-01

The broadband bistatic target strengths (TSs) of two submerged unexploded ordnance (UXO) targets have been measured in the NRL sediment pool facility. The targets-a 5 in. rocket and a 155 mm projectile-were among the targets whose monostatic TSs were measured and reported previously by the authors. Bistatic TS measurements were made for 0 degrees (target front) and 90 degrees (target side) incident source directions, and include both backscattered and forward scattered echo angles over a complete 360 degrees with the targets placed proud of the sediment surface. For the two source angles used, each target exhibits two strong highlights: a backscattered specular-like echo and a forward scattered response. The TS levels of the former are shown to agree reasonably well with predictions, based on scattering from rigid disks and cylinders, while the levels of the latter with predictions from radar cross section models, based on simple geometric optics appropriately modified. The bistatic TS levels observed for the proud case provide comparable or higher levels of broadband TS relative to free-field monostatic measurements. It is concluded that access to bistatic echo information in operations aimed at detecting submerged UXO targets could provide an important capability.

Aquatic macrophytes in cool aseasonal and seasonal streams: a comparison between Ecuadorian highland and Danish lowland streams

DEFF Research Database (Denmark)

Jacobsen, Dean; Terneus, Esteban

2001-01-01

-forms (submerged, amphibious, semiaquatic) was, however, different as submerged plants were less diverse in the Ecuadorian streams. Further, all submerged plants found in the Ecuadorian streams belonged to cosmopolitan genera with a mainly north-temperate distribution. We suggest that the low number of submerged...

Mechanisms behind pH changes by plant roots and shoots caused by elevated concentration of toxic elements

OpenAIRE

Javed, Muhammad Tariq

2011-01-01

Toxic elements are present in polluted water from mines, industrial outlets, storm water etc. Wetland plants take up toxic elements and increase the pH of the medium. In this thesis was investigated how the shoots of submerged plants and roots of emergent plants affected the pH of the surrounding water in the presence of free toxic ions. The aim was to clarify the mechanisms by which these plants change the surrounding water pH in the presence of toxic ions. The influence of Elodea canadensis...

Method of recovering deeply submerged support strings of a self-lifting floating unit from the ground

Energy Technology Data Exchange (ETDEWEB)

Dzhafarov, A M; Leybenzon, S R; Sarkisov, V G

1982-01-01

A method is proposed for recovering from the ground deeply submerged strings of self-lifting floating unit consisting of application of vertical forces through a lifter to the support string from surplus buoyancy of the housing submerged into the water. It is distinguished by the fact that in order to improve reliability and to expand the area of operation in water areas with deep occurrence of the bearing ground, submersion of the housing is done with its inclination. This applies to the support string or a group of support strings a permissible momentum, after which water ballast is used towards the housing opposite the inclined, with simultaneous preservation of the permissible moment applied to the support string or group of support strings, and the permissible momentum is determined from the formula-..mu.. = ..sqrt..theta/sup 2/ + /PSI//sup 2//A where M--momentum permitted according to the conditions of strength of the support string; /PSI/--angle of trim; /ETA/-- angle of list; A--coefficient of flexibility of the string submerged into the ground.

Aquatic arsenic: phytoremediation using floating macrophytes.

Science.gov (United States)

Rahman, M Azizur; Hasegawa, H

2011-04-01

Phytoremediation, a plant based green technology, has received increasing attention after the discovery of hyperaccumulating plants which are able to accumulate, translocate, and concentrate high amount of certain toxic elements in their above-ground/harvestable parts. Phytoremediation includes several processes namely, phytoextraction, phytodegradation, rhizofiltration, phytostabilization and phytovolatilization. Both terrestrial and aquatic plants have been tested to remediate contaminated soils and waters, respectively. A number of aquatic plant species have been investigated for the remediation of toxic contaminants such as As, Zn, Cd, Cu, Pb, Cr, Hg, etc. Arsenic, one of the deadly toxic elements, is widely distributed in the aquatic systems as a result of mineral dissolution from volcanic or sedimentary rocks as well as from the dilution of geothermal waters. In addition, the agricultural and industrial effluent discharges are also considered for arsenic contamination in natural waters. Some aquatic plants have been reported to accumulate high level of arsenic from contaminated water. Water hyacinth (Eichhornia crassipes), duckweeds (Lemna gibba, Lemna minor, Spirodela polyrhiza), water spinach (Ipomoea aquatica), water ferns (Azolla caroliniana, Azolla filiculoides, and Azolla pinnata), water cabbage (Pistia stratiotes), hydrilla (Hydrilla verticillata) and watercress (Lepidium sativum) have been studied to investigate their arsenic uptake ability and mechanisms, and to evaluate their potential in phytoremediation technology. It has been suggested that the aquatic macrophytes would be potential for arsenic phytoremediation, and this paper reviews up to date knowledge on arsenic phytoremediation by common aquatic macrophytes. Copyright © 2011 Elsevier Ltd. All rights reserved.

Effects of light quality on leaf morphogenesis of a heterophyllous amphibious plant, Rotala hippuris.

Science.gov (United States)

Momokawa, Naoko; Kadono, Yasuro; Kudoh, Hiroshi

2011-11-01

For heterophyllous amphibious plants that experience fluctuating water levels, it is critical to control leaf development precisely in response to environmental cues that can serve as a quantitative index of water depth. Light quality can serve as such a cue because the ratio of red light relative to far-red light (R/FR) increases and blue-light intensity decreases with increasing water depth. Growth experiments were conducted to examine how R/FR and blue-light intensity alter leaf morphology of a heterophyllous amphibious plant, Rotala hippuris. Using combinations of far red (730 nm), red (660 nm) and blue (470 nm) light-emitting diodes (LEDs), growth experiments were used to quantitatively evaluate the effects of the R/FR ratio and blue-light intensity on leaf morphology. Under the natural light regime in an outside growth garden, R. hippuris produced distinct leaves under submerged and aerial conditions. R/FR and blue-light intensity were found to markedly affect heterophyllous leaf formation. Higher and lower R/FR caused leaf characters more typical of submerged and aerial leaves, respectively, in both aerial and submerged conditions, in accordance with natural distribution of leaf types and light under water. High blue light caused a shift of trait values toward those of typical aerial leaves, and the response was most prominent under conditions of R/FR that were expected near the water surface. R/FR and blue-light intensity provides quantitative cues for R. hippuris to detect water depth and determine the developmental fates of leaves, especially near the water surface. The utilization of these quantitative cues is expected to be important in habitats where plants experience water-level fluctuation.

Plant community, primary productivity, and environmental conditions following wetland re-establishment in the Sacramento-San Joaquin Delta, California

Science.gov (United States)

Miller, R.L.; Fujii, R.

2010-01-01

Wetland restoration can mitigate aerobic decomposition of subsided organic soils, as well as re-establish conditions favorable for carbon storage. Rates of carbon storage result from the balance of inputs and losses, both of which are affected by wetland hydrology. We followed the effect of water depth (25 and 55 cm) on the plant community, primary production, and changes in two re-established wetlands in the Sacramento San-Joaquin River Delta, California for 9 years after flooding to determine how relatively small differences in water depth affect carbon storage rates over time. To estimate annual carbon inputs, plant species cover, standing above- and below-ground plant biomass, and annual biomass turnover rates were measured, and allometric biomass models for Schoenoplectus (Scirpus) acutus and Typha spp., the emergent marsh dominants, were developed. As the wetlands developed, environmental factors, including water temperature, depth, and pH were measured. Emergent marsh vegetation colonized the shallow wetland more rapidly than the deeper wetland. This is important to potential carbon storage because emergent marsh vegetation is more productive, and less labile, than submerged and floating vegetation. Primary production of emergent marsh vegetation ranged from 1.3 to 3.2 kg of carbon per square meter annually; and, mid-season standing live biomass represented about half of the annual primary production. Changes in species composition occurred in both submerged and emergent plant communities as the wetlands matured. Water depth, temperature, and pH were lower in areas with emergent marsh vegetation compared to submerged vegetation, all of which, in turn, can affect carbon cycling and storage rates. ?? Springer Science+Business Media B.V. 2009.

Solving underwater crimes: development of latent prints made on submerged objects.

Science.gov (United States)

Castelló, Ana; Francés, Francesc; Verdú, Fernando

2013-09-01

Underwater crime scenes always present a challenge for forensic researchers, as the destructive effect of water considerably complicates the chances of recovering material of evidential value. The aim of this study is to tackle the problem of developing marks that have been left on submerged objects. Fingermark deposition was randomly made on two surfaces - glass and plastic whilst the material was submerged under tap water and then left for one to fifteen days before drying and development. For their later development, various reagents - Black Powder, Silver Metallic Powder, Fluorescent Powder, Sudan Black (powder and solution) and Small Particle Reagent - were used and the effectiveness of each of them on this particular type of evidence was then evaluated. The results show the possibility of obtaining good quality developed marks, even under such adverse circumstances. Further and wider research should, therefore, be undertaken in which other variables are introduced such as different substrates, other types of liquids, and environmental or time factors. Copyright © 2013 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

Solid-State Fermentation vs Submerged Fermentation for the Production of l-Asparaginase.

Science.gov (United States)

Doriya, K; Jose, N; Gowda, M; Kumar, D S

l-Asparaginase, an enzyme that catalyzes l-asparagine into aspartic acid and ammonia, has relevant applications in the pharmaceutical and food industry. So, this enzyme is used in the treatment of acute lymphoblastic leukemia, a malignant disorder in children. This enzyme is also able to reduce the amount of acrylamide found in carbohydrate-rich fried and baked foods which is carcinogenic to humans. The concentration of acrylamide in food can be reduced by deamination of asparagine using l-Asparaginase. l-Asparaginase is present in plants, animals, and microbes. Various microorganisms such as bacteria, yeast, and fungi are generally used for the production of l-Asparaginase as it is difficult to obtain the same from plants and animals. l-Asparaginase from bacteria causes anaphylaxis and other abnormal sensitive reactions. To overcome this, eukaryotic organisms such as fungi can be used for the production of l-Asparaginase. l-Asparaginase can be produced either by solid-state fermentation (SSF) or by submerged fermentation (SmF). SSF is preferred over SmF as it is cost effective, eco-friendly and it delivers high yield of enzyme. SSF process utilizes agricultural and industrial wastes as solid substrate. The contamination level is substantially reduced in SSF through low moisture content. Current chapter will discuss in detail the chemistry and applications of l-Asparaginase enzyme and various methods available for the production of the enzyme, especially focusing on the advantages and limitations of SSF and SmF processes. © 2016 Elsevier Inc. All rights reserved.

A submerged tubular ceramic membrane bioreactor for high strength wastewater treatment.

Science.gov (United States)

Sun, D D; Zeng, J L; Tay, J H

2003-01-01

A 4 L submerged tubular ceramic membrane bioreactor (MBR) was applied in laboratory scale to treat 2,400 mg-COD/L high strength wastewater. A prolonged sludge retention time (SRT) of 200 day, in contrast to the conventional SRT of 5 to 15 days, was explored in this study, aiming to reduce substantially the amount of disposed sludge. The MBR system was operated for a period of 142 days in four runs, differentiated by specific oxygen utilization rate (SOUR) and hydraulic retention time (HRT). It was found that the MBR system produced more than 99% of suspended solid reduction. Mixed liquor suspended solids (MLSS) was found to be adversely proportional to HRT, and in general higher than the value from a conventional wastewater treatment plant. A chemical oxygen demand (COD) removal efficiency was achieved as high as 98% in Run 1, when SOUR was in the range of 100-200 mg-O/g-MLVSS/hr. Unexpectedly, the COD removal efficiency in Run 2 to 4 was higher than 92%, on average, where higher HRT and abnormally low SOUR of 20-30 mg-O/g-MLVSS/hr prevailed. It was noted that the ceramic membrane presented a significant soluble nutrient rejection when the microbial metabolism of biological treatment broke down.

Analysis of enzyme production by submerged culture of Aspergillus oryzae using whole barley.

Science.gov (United States)

Masuda, Susumu; Kikuchi, Kaori; Matsumoto, Yuko; Sugimoto, Toshikazu; Shoji, Hiroshi; Tanabe, Masayuki

2009-10-01

We have reported on high enzyme production by submerged culture of Aspergillus kawachii using barley with the husk (whole barley). To elucidate the mechanism underlying this high enzyme production, we performed a detailed analysis. Aspergillus oryzae RIB40 was submerged-cultured using whole barley and milled whole barley. Enzyme production was analyzed in terms of changes in medium components and gene expression levels. When whole barley was used, high production of glucoamylase and alpha-amylase and high gene expression levels of these enzymes were observed. Low ammonium concentrations were maintained with nitrate ion uptake continuing into the late stage using whole barley. These findings suggest that the sustainability of nitrogen metabolism is related to high enzyme production, and that a mechanism other than that associated with the conventional amylase expression system is involved in this relationship.

Modeling the element cycle of aquatic plants

International Nuclear Information System (INIS)

Asaeda, Takashi

2007-01-01

Aquatic plants play an important role in element cycles in wetlands and the efficiency of the process is extremely related to their proportional biomass allocation to above- and belowground organs. Therefore, the framework of most macrophyte productivity models is usually similar with a mass-balance approach consisting of gross production, respiration and mortality losses and the translocation between organs. These growth models are incorporated with decomposition models to evaluate the annual cycle of elements. Perennial emergent macrophytes with a relatively large biomass have a particularly important role in element cycles. Their phenological stages, such as the beginning of hibernation of belowground rhizome systems, emergence of new shoots in spring with resources stocked in the rhizomes, flowering, downward translocation of photosynthetic products later on and then the mortality of the aboveground system in late autumn, depend on the environmental conditions, basically the nutrients, water depth, climatic variations, etc. Although some species retain standing dead shoots for a long time, dead shoots easily fall into water, starting to decompose in the immediate aftermath. However, their decomposition rates in the water are relatively low, causing to accumulate large amounts of organic sediments on the bottom. Together with the deposition of allochthonous suspended matters in the stand, this process decreases the water depth, transforming wetlands gradually into land. The depth of penetration of roots into the sediments to uptake nutrients and water is extremely site specific, however, in water-logged areas, the maximum penetrable depth may be approximately estimated by considering the ability of oxygen transport into the rhizome system. The growth of perennial submerged plants is also estimated by a process similar to that of emergent macrophytes. However, compared with emergent macrophytes, the root system of submerged macrophytes is weaker, and the nutrient

The USGS role in mapping the nation's submerged lands

Science.gov (United States)

Schwab, Bill; Haines, John

2004-01-01

The seabed provides habitat for a diverse marine life having commercial, recreational, and intrinsic value. The habitat value of the seabed is largely a function of the geological structure and related geological, biological, oceanologic, and geochemical processes. Of equal importance, the nation's submerged lands contain energy and mineral resources and are utilized for the siting of offshore infrastructure and waste disposal. Seabed character and processes influence the safety and viability of offshore operations. Seabed and subseabed characterization is a prerequisite for the assessment, protection, and utilization of both living and non-living marine resources. A comprehensive program to characterize and understand the nation's submerged lands requires scientific expertise in the fields of geology, biology, hydrography, and oceanography. The U.S. Geological Survey (USGS) has long experience as the Federal agency charged with conducting geologic research and mapping in both coastal and offshore regions. The USGS Coastal and Marine Geology Program (CMGP) leads the nation in expertise related to characterization of seabed and subseabed geology, geological processes, seabed dynamics, and (in collaboration with the National Oceanic and Atmospheric Administration (NOAA) and international partners) habitat geoscience. Numerous USGS studies show that sea-floor geology and processes determine the character and distribution of biological habitats, control coastal evolution, influence the coastal response to storm events and human alterations, and determine the occurrence and concentration of natural resources.

CFD Modeling of Swirl and Nonswirl Gas Injections into Liquid Baths Using Top Submerged Lances

Science.gov (United States)

Huda, Nazmul; Naser, J.; Brooks, G.; Reuter, M. A.; Matusewicz, R. W.

2010-02-01

Fluid flow phenomena in a cylindrical bath stirred by a top submerged lance (TSL) gas injection was investigated by using the computational fluid dynamic (CFD) modeling technique for an isothermal air-water system. The multiphase flow simulation, based on the Euler-Euler approach, elucidated the effect of swirl and nonswirl flow inside the bath. The effects of the lance submergence level and the air flow rate also were investigated. The simulation results for the velocity fields and the generation of turbulence in the bath were validated against existing experimental data from the previous water model experimental study by Morsi et al.[1] The model was extended to measure the degree of the splash generation for different liquid densities at certain heights above the free surface. The simulation results showed that the two-thirds lance submergence level provided better mixing and high liquid velocities for the generation of turbulence inside the water bath. However, it is also responsible for generating more splashes in the bath compared with the one-third lance submergence level. An approach generally used by heating, ventilation, and air conditioning (HVAC) system simulations was applied to predict the convective mixing phenomena. The simulation results for the air-water system showed that mean convective mixing for swirl flow is more than twice than that of nonswirl in close proximity to the lance. A semiempirical equation was proposed from the results of the present simulation to measure the vertical penetration distance of the air jet injected through the annulus of the lance in the cylindrical vessel of the model, which can be expressed as L_{va} = 0.275( {do - di } )Frm^{0.4745} . More work still needs to be done to predict the detail process kinetics in a real furnace by considering nonisothermal high-temperature systems with chemical reactions.

Analysis of submerged implant towards mastication load using 3D finite element method (FEM

Directory of Open Access Journals (Sweden)

Widia Hafsyah Sumarlina Ritonga

2016-11-01

Full Text Available Introduction: The surgical procedure for implantation of a surgical implant comprising a stage for the implant design nonsubmerged and two stages for submerged. Submerged implant design often used in Faculty of Dentistry Universitas Padjadjaran because it is safer in achieving osseointegration. This study was conducted to evaluate the failure of dental implant based on location and the value of internal tensiones as well as supporting tissues when given mastication load by using the 3D Finite Element Method (FEM. Methods: This study used a photograph of the mandibular CBCT patient and CT Scan Micro one implant submerged. Radiograph image was then converted into a digital model of the 3D computerized finite element, inputted the material properties, pedestal, then simulated the occlusion load  as much as 87N and 29N of frictional Results: The maximum tension location on the implant was located on the  exact side of the contact area between the implant and alveolar crest. The maximum tension value was 193.31MPa on the implant body. The value was below the limit value of the ability of the titanium alloy to withstand fracture (860 MPa. Conclusion: The location of the maximum tension on the body of the implant was located on the exact contact area between the implant-abutment and alveolar crest. Under the mastication load, this implant design found no failure.

Growth physiology and dimorphism of Mucor circinelloides (syn. racemosus) during submerged batch cultivation

DEFF Research Database (Denmark)

Mcintyre, Mhairi; Breum, J.; Arnau, J.

2002-01-01

Mucor circinelloides is being investigated as a possible host for the production of heterologous proteins. Thus, the environmental conditions defining the physiology and morphology of this dimorphic fungus have been investigated in submerged batch cultivation. The optimal conditions for growth...

Wave transmission over permeable submerged breakwaters; Transmision del oleaje en rompeolas sumergidos permeables

Energy Technology Data Exchange (ETDEWEB)

Ruiz-y-Zurvia-Flores, Jaime Roberto; Fragoso-Sandoval, Lucio [Instituto Politecnico Nacional(Mexico)

2008-10-15

The permeable submerged breakwaters represent a coastal protection alternative, where some degree of wave energy transmission is acceptable. Such would be the case of tourist beach protection in Mexico. In previous researches, like those performed by D'Angremond et al. (1996), Seabrook and Hall (1998), and Briganti et al. (2003), the empirical formulas developed, give only some limited information over the spatial distribution of wave energy over the structure. Therefore, a decision was made to conduct a study on a reduced physical model of a permeable submerged breakwater based on the results presented by those researchers and with possible applications. Therefore this paper presents the development of a study of wave transmission over permeable submerged breakwaters performed in a reduced physical model of different sections of a submerged rockfill breakwater of the trapezoidal type. This was done in a narrow wave flume with a hydraulic irregular wave generator controlled by a computer that was used to generate and to reproduce different types of irregular waves to be used in the tests. It also has a wave meter with four sensors, and they are connected to a computer in order to process the wave data. The main objective of the study was to determine in an experimental way the influence of the several parameters of submerged breakwater over the wave transmission coefficient. Our experimental results were comparable to those obtained by D'Angremond et al. (1996) and Seabrook and Hall (1998). The results show that the sumerged breakwater parameters of most influence over the wave transmission coefficient were relative submergence and the relative width crest of the sumerged breakwater, and that the formula by Seabrook and Hall correlates best with our results. [Spanish] Los rompeolas sumergidos permeables representan actualmente una alternativa de proteccion de costas, donde un cierto grado de transmision de energia del oleaje es aceptable, como seria el

Monitoring the effects of floods on submerged macrophytes in a large river.

Science.gov (United States)

Ibáñez, Carles; Caiola, Nuno; Rovira, Albert; Real, Montserrat

2012-12-01

The lower Ebro River (Catalonia, Spain) has recently undergone a regime shift from a phytoplankton to a macrophyte-dominated system. Macrophytes started to spread at the end of the 1990s and since 2002 artificial floods (flushing flows) of short duration (1-2 days) are released from the Riba-roja dam once or twice a year in order to reduce macrophyte density. The aim of this study was to analyse the spatiotemporal trends of the submerged macrophytes in two stretches of the lower Ebro River using high-resolution hydroacoustic methods, in order to elucidate the effects of artificial floods and natural floods on its distribution and abundance. Results showed that the mean cover in the two studied stretches (Móra and Ginestar) was not reduced after a flushing flow (from 36.59% to 55.85% in Móra, and from 21.18% to 21.05% in Ginestar), but it was greatly reduced after the natural flood (down to 9.79% in Móra and 2.04% in Ginestar); surprisingly the cover increased in Móra after the artificial flood. In order to increase the efficiency of floods in controlling macrophyte spreading, the magnitude and frequency of them should largely increase, as well as the suspended sediment load, approaching as much as possible to the original flood pattern before dam construction. Hydroacoustic methods combined with geostatistics and interpolation in GIS can accurately monitor spatiotemporal trends of submerged macrophytes in large rivers. This is the first article to apply this monitoring system to submerged macrophytes in rivers. Copyright © 2012 Elsevier B.V. All rights reserved.

The Acoustic Properties of Water Submerged Lodgepole Pine (Pinus contorta and Spruce (Picea spp. Wood and Their Suitability for Use as Musical Instruments

Directory of Open Access Journals (Sweden)

Calvin Hilde

2014-08-01

Full Text Available Wood is a common material used for the manufacture of many products, and submerged wood, in particular, has been used in niche markets and musical instruments. In order to examine if submerged wood in British Columbia, Canada, would be appropriate for use as musical instruments, a study was performed in 2007 on submerged wood from Ootsa Lake, British Columbia, Canada. The results of that study showed the wood was not suitable for musical instruments. In this paper, the wood samples were allowed to age untouched in a laboratory setting and were then retested under the hypothesis that physical acoustic characteristics would improve. It was shown, however, that acoustic properties became less adequate after being left to dry over time. This article describes the density, speed of sound, acoustic constant and characteristic impedance properties for submerged wood and a comparison is made for different applications for musical instruments.

Heterologous expression of VHb can improve the yield and quality of biocontrol fungus Paecilomyces lilacinus, during submerged fermentation.

Science.gov (United States)

Zhang, Shumeng; Wang, Jieping; Wei, Yale; Tang, Qing; Ali, Maria Kanwal; He, Jin

2014-10-10

Paecilomyces lilacinus is an egg-parasitic fungus which is effective against plant-parasitic nematodes and it has been successfully commercialized for the control of many plant-parasitic nematodes. However, during the large-scale industrial fermentation process of the filamentous fungus, the dissolved oxygen supply is a limiting factor, which influences yield, product quality and production cost. To solve this problem, we intended to heterologously express VHb in P. lilacinus ACSS. After optimizing the vgb gene, we fused it with a selection marker gene nptII, a promoter PgpdA and a terminator TtrpC. The complete expression cassette PgpdA-nptII-vgb-TtrpC was transferred into P. lilacinus ACSS by Agrobacterium tumefaciens-mediated transformation. Consequently, we successfully screened an applicable fungus strain PNVT8 which efficiently expressed VHb. The submerged fermentation experiments demonstrated that the expression of VHb not only increased the production traits of P. lilacinus such as biomass and spore production, but also improved the beneficial product quality and application value, due to the secretion of more protease and chitinase. It can be speculated that the recombinant strain harboring vgb gene will have a growth advantage over the original strain under anaerobic conditions in soil and therefore will possess higher biocontrol efficiency against plant-parasitic nematodes. Copyright © 2014 Elsevier B.V. All rights reserved.

Archaeology. Sedimentary DNA from a submerged site reveals wheat in the British Isles 8000 years ago.

Science.gov (United States)

Smith, Oliver; Momber, Garry; Bates, Richard; Garwood, Paul; Fitch, Simon; Pallen, Mark; Gaffney, Vincent; Allaby, Robin G

2015-02-27

The Mesolithic-to-Neolithic transition marked the time when a hunter-gatherer economy gave way to agriculture, coinciding with rising sea levels. Bouldnor Cliff, is a submarine archaeological site off the Isle of Wight in the United Kingdom that has a well-preserved Mesolithic paleosol dated to 8000 years before the present. We analyzed a core obtained from sealed sediments, combining evidence from microgeomorphology and microfossils with sedimentary ancient DNA (sedaDNA) analyses to reconstruct floral and faunal changes during the occupation of this site, before it was submerged. In agreement with palynological analyses, the sedaDNA sequences suggest a mixed habitat of oak forest and herbaceous plants. However, they also provide evidence of wheat 2000 years earlier than mainland Britain and 400 years earlier than proximate European sites. These results suggest that sophisticated social networks linked the Neolithic front in southern Europe to the Mesolithic peoples of northern Europe. Copyright © 2015, American Association for the Advancement of Science.

EAARL-B Submerged Topography - Saint Croix and Saint Thomas, U.S. Virgin Islands, 2014

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Binary point-cloud data for part of the submerged environs of Saint Croix and Saint Thomas, U.S. Virgin Islands, were produced from remotely sensed, geographically...

Statistical optimization of lovastatin production by Omphalotus olearius (DC.) singer in submerged fermentation.

Science.gov (United States)

Atlı, Burcu; Yamaç, Mustafa; Yıldız, Zeki; Isikhuemhen, Omoanghe S

2016-01-01

In this study, culture conditions were optimized to improve lovastatin production by Omphalotus olearius, isolate OBCC 2002, using statistical experimental designs. The Plackett-Burman design was used to select important variables affecting lovastatin production. Accordingly, glucose, peptone, and agitation speed were determined as the variables that have influence on lovastatin production. In a further experiment, these variables were optimized with a Box-Behnken design and applied in a submerged process; this resulted in 12.51 mg/L lovastatin production on a medium containing glucose (10 g/L), peptone (5 g/L), thiamine (1 mg/L), and NaCl (0.4 g/L) under static conditions. This level of lovastatin production is eight times higher than that produced under unoptimized media and growth conditions by Omphalotus olearius. To the best of our knowledge, this is the first attempt to optimize submerged fermentation process for lovastatin production by Omphalotus olearius.

Using algae and submerged calcifying water flora for treating neutral to alkaline uranium-contaminated water; Verwendung von Algen und submersen kalzifizierenden Wasserpflanzen zur Aufbereitung neutraler bis basischer uranhaltiger Waesser

Energy Technology Data Exchange (ETDEWEB)

Dienemann, C.; Dienemann, H.; Stolz, L.; Dudel, E.G. [TU Dresden (DE). Inst. fuer Allgemeine Oekologie und Umweltschutz, Tharandt (Germany)

2005-07-01

Elimination of uranium from neutral to alkaline water is a complex technical process involving decarbonation, usually with HCl, followed by uranium removal by adding alkaline substances. In passive water treatment systems, uranium species - which often consist of a combination of oxidation and reduction stages - are not sufficiently considered. Algae and submerged water plants provide a natural alternative. They remove carbon dioxides or hydrogen carbonate, depending on the species, thus reducting the concentrations of the carbonate species. As the uranium species in alkaline water are coupled on the one hand to the carbonate species and on the other hand on the earth alkali metals, algae and submerged calcifying water plants are an excellent preliminary stage as a supplement to conventional passive water treatment systems. For a quantification of this effect, laboratory experiments were made with Cladophara spec. and with uranium concentrations of 100, 250 and 1000 {mu}g U.L{sup -1} at pH 8.3. The pH was adjusted with NaOH resp. Na2CO3 resulting in different uranium species. After 20 minutes, there was a difference in self-absorption between the different species (higher uranium concentration for NaOH than for Na2CO3), which was no longer observeable after 24 h. On the basis of data on the biomass development of macrophytic algae (Cladophora and Microspora) in a flowing river section near Neuensalz/Vogtland district, the final dimensions of a purification stage of this type are assessed. (orig.)

Aquatic macrophytes in the large, sub-tropical Itaipu Reservoir, Brazil

Directory of Open Access Journals (Sweden)

Roger Paulo Mormul

2010-12-01

Full Text Available In the last three decades, rapid assessment surveys have become an important approach for measuring aquatic ecosystem biodiversity. These methods can be used to detect anthropogenic impacts and recognize local or global species extinctions. We present a floristic survey of the aquatic macrophytes along the Brazilian margin of the Itaipu Reservoir conducted in 2008 and compare this with a floristic survey conducted ten years earlier. We used ordination analysis to determine whether assemblage composition differed among reservoir arms. Macrophyte species were sampled in each of the 235 sampling stations using a boat, which was positioned inside three places of each macrophyte stand to record species and search for small plants. We also collected submerged plants using a rake with the boat moving at constant velocity for ten minutes. We assigned individual macrophyte species to life form and identified representative species for each life form. A total of 87 macrophyte taxa were identified. The "emergent" life forms contained the highest number of species, followed by "rooted submerged" life forms. The extensive survey of macrophytes undertaken in September 2008 recorded more species than a survey conducted between 1995 and 1998. This could be due to changes in water physico-chemistry, disturbances due to water drawdown and the long period between surveys, which may have allowed natural colonization by other species. Additionally, differences in the classification systems and taxonomic resolution used in the surveys may account for differences in the number of species recorded. Assemblage composition varied among the arms and was affected by underwater radiation (as measured using a Secchi disk and fetch. Five non-native species were found. Two of these non-native species (Urochloa subquadripara and Hydrilla verticillata are of special concern because they have a high frequency of occurrence and occupy large marginal areas of the reservoir. Future

Competition between free-floating and submerged macrophytes in a future of climate change

NARCIS (Netherlands)

Netten, J.J.C.

2011-01-01

This research was about the asymmetric competition between free-floating and submerged macrophytes in shallow freshwater ecosystems. I studied the effect of climate change on the dominance of free-floating macrophytes in temperate regions. The research approach was a combination of outdoor

[Dynamics of genome changes in Rauwolfia serpentina callus tissue upon the switch to conditions of submerged cultivation].

Science.gov (United States)

Spiridonova, E V; Adnof, D M; Andreev, I O; Kunakh, V A

2008-01-01

Genome of Rauwolfia serpentina callus cells was found to fail undergo the noticeable changes for several early passages upon the switch from surface to submerged cultivation in the liquid medium of special composition. After subsequent 4-6 passages in submerged culture RAPD spectra polymorphism was revealed which may reflect the changes in DNA sequence as well as in the structure of cell population that forms the strain. Introduction of the intermediary passage on the agar-solidified medium of more simple composition prior to transfer into liquid medium appeared not to affect essentially the level and the pattern of genome changes.

Responsiveness of performance and morphological traits to experimental submergence predicts field distribution pattern of wetland plants

NARCIS (Netherlands)

Luo, Fang-Li; Huang, Lin; Lei, Ting; Xue, Wei; Li, Hong-Li; Yu, Fei-Hai; Cornelissen, J.H.C.

2016-01-01

Question: Plant trait mean values and trait responsiveness to different environmental regimes are both important determinants of plant field distribution, but the degree to which plant trait means vs trait responsiveness predict plant distribution has rarely been compared quantitatively. Because

Submerged arc narrow gap welding of the steel DIN 20MnMoNi55

International Nuclear Information System (INIS)

Moraes, M.M.

1987-01-01

The methodology for submerged arc narrow gap welding for high thickness rolled steel DIN 20MnMoNi55 was developed, using din S3NiMo1 04 mm and 05 mm wires, and DIN 8B435 flux. For this purpose, submerged arc narrow gap welded joints with 50 mm and 120 mm thickness were made aiming the welding parameters optimization and the study of the influence of welding voltage, wire diameter and wire to groove face distance on the operational performance and on the welded joint quality, specially on the ISO-V impact toughness. These welded joints were checked by non-destructive mechanical and metallographic tests. Results were compared with those obtained by one 120 mm thickness submerged arc conventional gap welded joint, using the same base metal and consumables (05 mm wire). The analysis of the results shows that the increasing of the wire to groove face distance and the welding voltage increases the hardness and the ISO-V impact toughness of the weld metal. It shows that the reduction of the gap angle is the main cause for the obtained of a heat affected zone free from coarse grains, the reduction of the welding voltage, the increasing of the wire to groove face distance, and the grounding optimization also contribute for that. It was also concluded that the quality and the execution complexity level of a narrow gap welded joint are identical to a conventional gap welded joint. (author) [pt

Diminishing peat oxidation of agricultural peat soils by infiltration via submerged drains

NARCIS (Netherlands)

Akker, van den J.J.H.; Hendriks, R.F.A.

2017-01-01

Oxidation of peat soils used in dairy farming in the western peat area of The Netherlands causes subsidence rates up to 13 mm.y and emissions of CO2 to about 27 t.ha.y. In 2003 experiments started with subsurface irrigation by submerged drains to raise groundwater levels to reduce oxidation and so

What role do beds of submerged macrophytes play in structuring estuarine fish assemblages? Lessons from a warm-temperate South African estuary

Science.gov (United States)

Sheppard, Jill N.; James, Nicola C.; Whitfield, Alan K.; Cowley, Paul D.

2011-11-01

Habitat variability is one of the factors influencing species richness within estuarine systems, and a loss of habitat can result in a restructuring of the estuarine ichthyofaunal assemblage, particularly if these conditions persist over long time periods. The potential effects of the loss of extensive submerged macrophyte beds ( Ruppia cirrhosa and Potamogeton pectinatus) on an estuarine fish assemblage were investigated through an analysis of a long-term seine net catch dataset from the temporarily open/closed East Kleinemonde Estuary, South Africa. Catch data for a 12-year period, encompassing six years of macrophyte presence and six years of macrophyte senescence, indicated that the loss of this habitat did not influence species richness but changes in the relative abundance of certain species were evident. A shift in dominance from vegetation-associated species to those associated with sandy environments ( e.g. members of the family Mugilidae) was observed. However, species wholly dependent on macrophytes such as the critically endangered estuarine pipefish Syngnathus watermeyeri were only recorded during years when macrophyte beds were present, while vegetation-associated species such as the sparid Rhabdosargus holubi persisted at lower levels of relative abundance. The reduced abundance of all vegetation-associated fish species during years of macrophyte senescence was probably reflective of declining food resources resulting from the loss of macrophyte beds and/or increased vulnerability to predation. Submerged beds of aquatic plants are therefore important habitats within temporarily open/closed estuaries, South Africa's dominant estuary type.

Involvement of Physical Parameters in Medium Improvement for Tannase Production by Aspergillus niger FETL FT3 in Submerged Fermentation

OpenAIRE

Darah, I.; Sumathi, G.; Jain, K.; Hong, Lim Sheh

2011-01-01

Aspergillus niger FETL FT3, a local extracellular tannase producer strain that was isolated from one of dumping sites of tannin-rich barks of Rhizophora apiculata in Perak, Malaysia. This fungus was cultivated in 250 mL Erlenmeyer flask under submerged fermentation system. Various physical parameters were studied in order to maximize the tannase production. Maximal yield of tannase production, that is, 2.81 U per mL was obtained on the fourth day of cultivation when the submerged fermentation...

Turbulence-induced noise of a submerged cylinder using a permeable FW–H method

Directory of Open Access Journals (Sweden)

Woen-Sug Choi

2016-05-01

Full Text Available Among underwater noise sources around submerged bodies, turbulence-induced noise has not been well investigated because of the difficulty of predicting it. In computational aeroacoustics, a number of studies has been conducted using the Ffowcs Williams–Hawkings (FW–H acoustic analogy without consideration of quadrupole source term due to the unacceptable calculation cost. In this paper, turbulence-induced noise is predicted, including that due to quadrupole sources, using a large eddy simulation (LES turbulence model and a developed formulation of permeable FW–H method with an open source computational fluid dynamics (CFD tool-kit. Noise around a circular cylinder is examined and the results of using the acoustic analogy method with and without quadrupole noise are compared, i.e. the FW–H method without quadrupole noise versus the permeable FW–H method that includes quadrupole sources. The usability of the permeable FW–H method for the prediction of turbulence-noise around submerged bodies is shown.

Liquid Film Diffusion on Reaction Rate in Submerged Biofilters

DEFF Research Database (Denmark)

Christiansen, Pia; Hollesen, Line; Harremoës, Poul

1995-01-01

Experiments were carried out in order to investigate the influence of liquid film diffusion on reaction rate in a submerged biofilter with denitrification and in order to compare with a theoretical study of the mass transfer coefficient. The experiments were carried out with varied flow, identified...... by the empty bed velocity of inflow and recirculation, respectively 1.3, 2.8, 5.6 and 10.9 m/h. The filter material consisted of 3 mm biostyren spheres. The results indicate that the influence of liquid film diffusion on reaction rate can be ignored....

Field studies of the thermal plume from the D. C. Cook submerged discharge with comparisons to hydraulic-model results

International Nuclear Information System (INIS)

Frigo, A.A.; Paddock, R.A.; McCown, D.L.

1975-06-01

The Donald C. Cook Nuclear Plant at Bridgman, Michigan, uses submerged-diffuser discharges as a means of disposing waste heat into Lake Michigan. Preliminary results of temperature surveys of the thermal plume at the D. C. Cook Plant are presented. Indications are that the spatial extent of the plume at the surface is much smaller than previous results for surface shoreline discharges, particularly in the near and intermediate portions of the plume. Comparisons of limited prototype data with hydraulic (tank)-model predictions indicate that the model predictions for centerline temperature decay at the surface are too high for the initial 200 m from the discharge, but are generally correct beyond this point to the limits of the model. In addition, the hydraulic-model results underestimate the areal extent of the near and intermediate portions of the plume at the surface. Because this is the first report of a new field program, several inadequacies in the field-measurement techniques are noted and discussed. New techniques that have been developed to remedy these deficiencies, and which will be implemented for future field work, are also described. (auth)

Distribution of C, N, P in aquatic plants of some lakes in the middle of Yangtze river

International Nuclear Information System (INIS)

Huang Liang; Wu Ying; Zhou Juzhen; Zhang Jing; Li Wei

2003-01-01

By analyzing three elements (C, N, P, 13 C) in the ten aquatic plants of nine lakes in the middle of Yangtze River, the concentrations of C, N and δ 13 C in leaves of aquatic macrophytes depend on the environment where they live in. The concentration of C and N in leaves of submerged macrophytes is significantly lower than that of leaves of floating and emergent macrophytes because of limitation of inorganic carbon; And at the same time, because δ 13 C of inorganic carbon in water is higher than that of CO 2 in air, δ 13 C of leaves of submerged macrophytes is higher than that of leaves of floating and emergent macrophytes. (authors)

Conidiation of Neurospora crassa induced by treatment with natrium fluoride in submerged culture

Energy Technology Data Exchange (ETDEWEB)

Timberlake, W E; Turian, G

1975-01-01

A transient treatment of pregerminated conidia of Neurospora crassa with NaF induced young, submerged cultures to prematurely differentiate conidia. The inductive treatment decreased the rate of respiration (with lower RQ), reduced the relative concentration of nucleoside triphosphates, and inhibited leucine incorporation into protein and adenosine incorporation into RNA.

Nitrogen fertilizer management for tidal submergence tolerant landrace rice (Oryza sativa L. cultivars

Directory of Open Access Journals (Sweden)

M.A.A. Mamun

2017-12-01

Full Text Available In tidal submergence ecosystem, nitrogen (N is a crucial nutrient for improved and sustainable rice production. Therefore, a series of on-farm and on-station field experiments were conducted to develop a suitable N management practice for tidal submergence tolerant landrace aman rice. In on-farm, urea deep placement (UDP through urea super granule before panicle initiation (PI stage was compared with no fertilizer application. Similarly, five N fertilizer management practices viz. (i. two splits of prilled urea (PU, (ii. UDP at 10 DAT, (iii. UDP before PI, (iv. full dose PU before PI and (v. No urea (control were compared at on-station trial. Tidal submergence tolerance aman rice varieties (Rajashail, Kutiagni, Sadamota and Lalmota were used as testing materials. In on farm experiment, aman cultivars produced 2.0–2.5 t ha−1 grain without N fertilizer. But, cultivated Rajashail, Kutiagni, Sadachikon, Sadapajam, Lalmota and Sadamota gave 3.0–3.5 t ha−1 grain yield with the UDP before PI in tidal prone areas. Though UDP required fertilizer and application cost but it gave profit upto 22,000 BDT ha−1 (Bangladeshi Taka. In on-station experiment, UDP before PI stage significantly increased rice yield and economic return although it was comparable to two splits of PU and top dressing of PU before PI stage. However, UDP at 10 DAT increased straw yield but failed to increase grain yield even compared to control. It could be concluded that UDP before PI stage of rice is an effective method for increasing rice yield and farm income in tidal prone areas.

The avoidance strategy of environmental constraints by an aquatic plant Potamogeton alpinus in running waters.

Science.gov (United States)

Robionek, Alicja; Banaś, Krzysztof; Chmara, Rafał; Szmeja, Józef

2015-08-01

Aquatic plants anchored in streams are under pressure from various constraints linked to the water flow and display strategies to prevent their damage or destruction. We assume that the responses of aquatic plants to fast-water flow are a manifestation of a trade-off consisting in either maximizing the resistance to damage (tolerance strategy) in minimizing the hydrodynamic forces (avoidance strategy), or both. Our main hypothesis was that Potamogeton alpinus demonstrate the avoidance strategy. We analyzed architecture traits of the modules of this clonal plant from slow- and fast-flowing streams. In fast-flowing waters, the avoidance strategy of P. alpinus is reflected by the following: (1) the presence of floating leaves that stabilize the vertical position of the stem and protect the inflorescence against immersion; (2) elongation of submerged leaves (weakens the pressure of water); and (3) shoot diameter reduction and increase in shoot density (weakens the pressure of water, increases shoot elasticity), and by contrast in slow-water flow include the following: (4) the absence of floating leaves in high intensity of light (avoiding unnecessary outlays on a redundant organ); (5) the presence of floating leaves in low intensity of light (avoidance of stress caused by an insufficient assimilation area of submerged leaves).

Deep water marine algal flora of the submerged banks off west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Ambiye, V.; Untawale, A.G.

A survey of submerged banks off India viz Cora Divh, Sessostris and Bassas de-Pedro resulted in obtaining information on the rich and diverse marine algal flora from various depths ranging from 18-70 m. A programme of onboard dredging was undertaken...

Distribution and functional traits of charophytes and vascular plants

DEFF Research Database (Denmark)

Båstrup-Spohr, Lars

rare species are specialists in particular environments, while the abundant species have traits such as broad salinity tolerance, tall shoots, vegetative reproduction and variable life form. Vascular plants, in contrast to charophytes, occupy the entire gradient from submerged to drained conditions......A large variety of plant species of very different evolutionary origin are found within and along the margins of aquatic ecosystems. These species have very different adaptations depending on the particular environmental condition under which they grow. This thesis examines the role...... of these adaptations or functional traits for the distribution on large scales and along specific environmental gradients. Characean algae (charophytes) are an ancient group of aquatic plants found in most aquatic ecosystems. I confirmed that they have declined markedly during the 20th century, most likely...

Continental shelf drowned landscapes: Submerged geomorphological and sedimentary record of the youngest cycles

NARCIS (Netherlands)

Cohen, K.M.; Lobo, F.J.

2013-01-01

Continental shelves today find themselves largely submerged as a consequence of the sea-level rise in the last 20,000 years, the time since the Last Glacial Maximum (LGM), the period of maximum ice mass and minimum ocean volume within the Last Glacial Cycle. Their geomorphology, however, is far from

Satellite remote sensing of submerged aquatic vegetation distribution and status in the Currituck Sound, NC.

Science.gov (United States)

2012-11-01

Submerged Aquatic Vegetation (SAV) is an important component in any estuarine ecosystem. As such, it is regulated by federal and state agencies as a jurisdictional resource, where impacts to SAV are compensated through mitigation. Historically, tradi...

Comparative evaluation of extracellular β-D-fructofuranosidase in submerged and solid-state fermentation produced by newly identified Bacillus subtilis strain.

Science.gov (United States)

Lincoln, Lynette; More, Sunil S

2018-04-17

To screen and identify a potential extracellular β-D-fructofuranosidase or invertase producing bacterium from soil, and comparatively evaluate the enzyme biosynthesis under submerged and solid-state fermentation. Extracellular invertase producing bacteria were screened from soil. Identification of the potent bacterium was performed based on microscopic examinations and 16S rDNA molecular sequencing. Bacillus subtilis LYN12 invertase secretion was surplus with wheat bran humidified with molasses medium (70%), with elevated activity at 48 h and 37 °C under solid-state fermentation, whereas under submerged conditions increased activity was observed at 24 h and 45 °C in the molasses medium. The study revealed a simple fermentative medium for elevated production of extracellular invertase from a fast growing Bacillus strain. Bacterial invertases are scarce and limited reports are available. By far, this is the first report on the comparative analysis of optimization of extracellular invertase synthesis from Bacillus subtilis strain by submerged and solid-state fermentation. The use of agricultural residues increased yields resulting in development of a cost-effective and stable approach. Bacillus subtilis LYN12 invertase possesses excellent fermenting capability to utilize agro-industrial residues under submerged and solid-state conditions. This could be a beneficial candidate in food and beverage processing industries. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Speciation of arsenic in water, sediment, and plants of the Moira watershed, Canada, using HPLC coupled to high resolution ICP-MS

Energy Technology Data Exchange (ETDEWEB)

Zheng, Jian; Hintelmann, Holger; Dimock, Brian; Dzurko, Mark Stephen [Department of Chemistry, Trent University, 1600 West Bank Drive, K9J 7B8, Peterborough, Ontario (Canada)

2003-09-01

High-performance liquid chromatography (HPLC) coupled with high-resolution sector field ICP-MS was applied to the speciation of arsenic in environmental samples collected from the Moira watershed, Ontario, Canada. Arsenic contamination in Moira River and Moira Lake from historic gold mine operations is of increasing environmental concern to the local community. In this study, the current arsenic contamination status in water, sediment, and plants was investigated. Elevated levels of arsenic in the surface water of up to 75 ng mL{sup -1} in Moira River and 50 ng mL{sup -1} in Moira Lake were detected, 98% of which was present as arsenate. High concentrations of arsenic (>300 ng mL{sup -1}), mainly present as arsenite, were detected in sediment porewaters. A sediment profile of As from the West basin of Moira Lake showed lower As concentrations compared with data from the 1990s. An optimized extraction procedure using a phosphoric acid-ascorbic acid mixture demonstrated that an unknown ''As-complex'' which may consist of As, sulfide and organic matter is potentially responsible for the release of arsenite from the sediment to the overlying water column. Arsenic concentrations in plant samples ranged from 2.6 to 117 mg kg{sup -1}, dry weight. Accumulation of arsenic was observed in submerged plants collected from Moira River and Moira Lake. Only a small part of the arsenic (6.3-16.1%) in the plants was extractable with methanol-water (9:1), and most of this arsenic (70-93%) was inorganic arsenic. A variety of organic arsenic compounds, including simple methylated compounds (methylarsonic acid and dimethylarsinic acid), trimethylarsine oxide, and tetramethylarsonium cation were detected at trace levels. No arsenobetaine and arsenocholine was found in any plant sample. An unknown compound, most probably an arsenosugar was detected in the two submerged plants, coontail (Ceratophyllum demersum) and long-stemmed waterwort (Elatine triandra). These

Modeling growth, lipid accumulation and lipid turnover in submerged batch cultures of Umbelopsis isabellina

NARCIS (Netherlands)

Meeuwse, P.; Akbari, P.; Tramper, J.; Rinzema, A.

2012-01-01

The production of lipids by oleaginous yeast and fungi becomes more important because these lipids can be used for biodiesel production. To understand the process of lipid production better, we developed a model for growth, lipid production and lipid turnover in submerged batch fermentation. This

In process acoustic emission in multirun submerged arc welding

International Nuclear Information System (INIS)

Asty, M.; Birac, C.

1980-01-01

In order to avoid the formation of deep grooves when repairing defects in welded joints in heavy plates, an investigation was made aiming to detect and locate the defects by in-process acoustic emission in multirun submerged arc welding. Twelve defects (lack of penetration, cracks, inclusions, lack of fusion together with inclusions, blowholes) were intentionally introduced when the first plate was welded. A space-time method for processing the acoustic activity during welding allowed the detection and the location of the intentional defects as well as of the most important accidental defects evidenced by ultrasonic testing [fr

Enhanced effects of biotic interactions on predicting multispecies spatial distribution of submerged macrophytes after eutrophication.

Science.gov (United States)

Song, Kun; Cui, Yichong; Zhang, Xijin; Pan, Yingji; Xu, Junli; Xu, Kaiqin; Da, Liangjun

2017-10-01

Water eutrophication creates unfavorable environmental conditions for submerged macrophytes. In these situations, biotic interactions may be particularly important for explaining and predicting the submerged macrophytes occurrence. Here, we evaluate the roles of biotic interactions in predicting spatial occurrence of submerged macrophytes in 1959 and 2009 for Dianshan Lake in eastern China, which became eutrophic since the 1980s. For the four common species occurred in 1959 and 2009, null species distribution models based on abiotic variables and full models based on both abiotic and biotic variables were developed using generalized linear model (GLM) and boosted regression trees (BRT) to determine whether the biotic variables improved the model performance. Hierarchical Bayesian-based joint species distribution models capable of detecting paired biotic interactions were established for each species in both periods to evaluate the changes in the biotic interactions. In most of the GLM and BRT models, the full models showed better performance than the null models in predicting the species presence/absence, and the relative importance of the biotic variables in the full models increased from less than 50% in 1959 to more than 50% in 2009 for each species. Moreover, co-occurrence correlation of each paired species interaction was higher in 2009 than that in 1959. The findings suggest biotic interactions that tend to be positive play more important roles in the spatial distribution of multispecies assemblages of macrophytes and should be included in prediction models to improve prediction accuracy when forecasting macrophytes' distribution under eutrophication stress.

Submergence of Roots for Alveolar Bone Preservation. I. Endodontically Treated Roots.

Science.gov (United States)

1977-05-10

With Endodontic Submerged Roots Scale 0 1 2 3 Periapical 15 0 1 0 Pericoronal 7 3 3 3 (3 cysts ) = 1 _ _ _ _ _ _ _ _ _ = REFERENCES 1. Lam, R.: Contour...with coronal portions of the roots. These epithe lial-lined cysts prevented the formation of osteo- cementum over the coronal surface . In this study...the endodontically treated roots appeared to be primarily a response to the excess root cana l sealer that was expressed coronally and periapically

Wirelessly powered submerged-light illuminated photobioreactors for efficient microalgae cultivation

DEFF Research Database (Denmark)

Murray, Alexandra Marie; Fotidis, Ioannis; Isenschmid, Alex

2017-01-01

A novel submerged-light photobioreactor (SL-PBR) with free-floating, wireless internal light sources powered by near-field resonant inductive coupling was investigated using a quick (Chlorella vulgaris) and a slow (Haematococcus pluvialis) growing microalgal species. During testing of the SL......, respectively. Thus, the wireless internal light source was proven to be up to fivefold more effective light delivery system compared to the conventional illumination system. Meanwhile, it was discovered that some of the internal light sources had ceased to function, which might have caused underestimation...

Improvements in the use of aquatic herbicides and establishment of future research directions

Science.gov (United States)

Getsinger, K.D.; Netherland, M.D.; Grue, C.E.; Koschnick, T.J.

2008-01-01

Peer-reviewed literature over the past 20 years identifies significant changes and improvements in chemical control strategies used to manage nuisance submersed vegetation. The invasive exotic plants hydrilla (Hydrilla verticillata L.f. Royle) and Eurasian watermilfoil (Myriophyllum spicatum L.) continue to spread and remain the plant species of greatest concern for aquatic resource managers at the national scale. Emerging exotic weeds of regional concern such as egeria (Egeria densa Planch.), curlyleaf pondweed (Potamogeton crispus L.), and hygrophila (Hygrophila polysperma (Roxb.) T. Anders), as well as native plants such as variable watermilfoil (Myriophyllum heterophyllum Michx), and cabomba (Cabomba caroliniana Gray) are invasive outside their home ranges. In addition, there is always the threat of new plant introductions such as African elodea (Lagarosiphon major (Ridley) Moss) or narrow-leaf anacharis (Egeria najas Planchon). The registration of the bleaching herbicide fluridone in the mid 1980s for whole-lake and large-scale management stimulated numerous lines of research involving reduction of use rates, plant selectivity, residue monitoring, and impacts on fisheries. In addition to numerous advances, the specificity of fluridone for a single plant enzyme led to the first documented case of herbicide resistance in aquatic plant management. The resistance of hydrilla to fluridone has stimulated a renewed interest by industry and others in the registration of alternative modes of action for aquatic use. These newer chemistries tend to be enzyme-specific compounds with favorable non-target toxicity profiles. Registration efforts have been facilitated by increased cooperation between key federal government agencies that have aquatic weed control and research responsibilities, and regulators within the U.S. Environmental Protection Agency (USEPA). We reviewed past and current research efforts to identify areas in need of further investigation and to establish

Morphologic and seismic evidence of rapid submergence offshore Cide-Sinop in the southern Black Sea shelf

Science.gov (United States)

Ocakoğlu, Neslihan; İşcan, Yeliz; Kılıç, Fatmagül; Özel, Oğuz

2018-06-01

Multi-beam bathymetric and multi-channel seismic reflection data obtained offshore Cide-Sinop have revealed important records on the latest transgression of the Black Sea for the first time. A relatively large shelf plain within the narrow southern continental shelf characterized by a flat seafloor morphology at -100 water depth followed by a steep continental slope leading to -500 m depth. This area is widely covered by submerged morphological features such as dunes, lagoons, possible aeolianites, an eroded anticline and small channels that developed by aeolian and fluvial processes. These morphological features sit upon an erosional surface that truncates the top of all seismic units and constitutes the seafloor over the whole shelf. The recent prograded delta deposits around the shelf break are also truncated by the similar erosional surface. These results indicate that offshore Cide-Sinop was once a terrestrial landscape that was then submerged. The interpreted paleoshoreline varies from -100 to -120 m. This variation can be explained by not only sea level changes but also the active faults observed on the seismic section. The effective protection of morphological features on the seafloor is the evidence of abrupt submergence rather than gradual. In addition, the absence of coastal onlaps suggests that these morphological features should have developed at low sea level before the latest sea level rise in the Black Sea.

Effects of submerged macrophytes on the abundance and community composition of ammonia-oxidizing prokaryotes in a eutrophic lake.

Science.gov (United States)

Zhao, Da-yong; Luo, Juan; Zeng, Jin; Wang, Meng; Yan, Wen-ming; Huang, Rui; Wu, Qinglong L

2014-01-01

Abundances and community compositions of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in unvegetated sediment and the rhizosphere sediments of three submerged macrophytes (Ceratophyllum demersum, Vallisneria spinulosa, and Potamogeton crispus) were investigated in a large, eutrophic freshwater lake, Lake Taihu. Abundances of archaeal ammonia monooxygenase alpha-subunit (amoA) gene (from 6.56 × 10(6) copies to 1.06 × 10(7) copies per gram of dry sediment) were higher than those of bacterial amoA (from 6.13 × 10(5) to 3.21 × 10(6) copies per gram of dry sediment) in all samples. Submerged macrophytes exhibited no significant effect on the abundance and diversity of archaeal amoA gene. C. demersum and V. spinulosa increased the abundance and diversity of bacterial amoA gene in their rhizosphere sediment. However, the diversity of bacterial amoA gene in the rhizosphere sediments of P. crispus was decreased. The data obtained in this study would be helpful to elucidate the roles of submerged macrophytes involved in the nitrogen cycling of eutrophic lake ecosystems.

Performance of Submerged Membrane Bioreactor Combined with Powdered Activated Carbon Addition for the Treatment of an Industrial Wastewater

Directory of Open Access Journals (Sweden)

Tri Widjaja

2010-02-01

Full Text Available Membrane technology is one of the alternative solutions to overcome industrial wastewater treatment developed nowadays. The addition of PAC (Powdered Activated Carbon in the activated sludge using Submerged Membrane Adsorption Hybrid Bioreactor (SMAHBR is expected to increase the organic material removal. The purpose of this study was to determine the performance of submerged membrane bioreactor and activated carbon adsorption capacity of organic materials in wastewater. This study used SIER (Surabaya Industrial Estate Rungkut – Surabaya, Indonesia waste as activated sludge operated at Mixed Liquor Suspended Solid (MLSS concentrations of 8000 and 15000 mg/l, and Chemical Oxygen Demand (COD concentrations of 1500, 2500 mg/l, Sludge Retention Time (SRT of 10;20; and 30 days and activated carbon variables of 0%; 2.5%; 5%; 7.5%; 10%. The results showed that the fouling potential occurred at high MLSS where the COD removal occurred at PAC addition of 10% reaching 91.86%. High Soluble Microbial Product (SMP accumulation (± 10 mg/l occurred in short SRT and high MLSS concentration. PAC addition resulted in decreased microorganisms in the reactor and better effluent of SMAHBR, as a result, the performance of the submerged membrane bioreactor would be restored.

Aquatic plant surface as a niche for methanotrophs

Directory of Open Access Journals (Sweden)

Naoko eYoshida

2014-02-01

Full Text Available This study investigated the potential local CH4 sink in various plant parts as a boundary environment of CH4 emission and consumption. By comparing CH4 consumption activities in cultures inoculated with parts from 39 plant species, we observed significantly higher consumption of CH4 associated with aquatic plants than other emergent plant parts such as woody plant leaves, macrophytic marine algae, and sea grass. In situ activity of CH4 consumption by methanotrophs associated with different species of aquatic plants was in the range of 3.7 – 37 μmol⋅h-1⋅g-1 dry weight, which was ca 5.7-370 fold higher than epiphytic CH4 consumption in submerged parts of emergent plants. The qPCR-estimated copy numbers of the particulate methane monooxygenase-encoding gene pmoA were variable among the aquatic plants and ranged in the order of 105 to 107 copies⋅g-1 dry weight, which correlated with the observed CH4 consumption activities. Phylogenetic identification of methanotrophs on aquatic plants based on the pmoA sequence analysis revealed a predominance of diverse gammaproteobacterial type-I methanotrophs, including a phylotype of a possible plant-associated methanotroph with the closest identity (86-89% to Methylocaldum gracile.

Bacterial communities associated with culex mosquito larvae and two emergent aquatic plants of bioremediation importance.

Directory of Open Access Journals (Sweden)

Dagne Duguma

Full Text Available Microbes are important for mosquito nutrition, growth, reproduction and control. In this study, we examined bacterial communities associated with larval mosquitoes and their habitats. Specifically, we characterized bacterial communities associated with late larval instars of the western encephalitis mosquito (Culextarsalis, the submerged portions of two emergent macrophytes (California bulrush, Schoenoplectuscalifornicus and alkali bulrush, Schoenoplectusmaritimus, and the associated water columns to investigate potential differential use of resources by mosquitoes in different wetland habitats. Using next-generation sequence data from 16S rRNA gene hypervariable regions, the alpha diversity of mosquito gut microbial communities did not differ between pond mesocosms containing distinct monotypic plants. Proteobacteria, dominated by the genus Thorsellia (Enterobacteriaceae, was the most abundant phylum recovered from C. tarsalis larvae. Approximately 49% of bacterial OTUs found in larval mosquitoes were identical to OTUs recovered from the water column and submerged portions of the two bulrushes. Plant and water samples were similar to one another, both being dominated by Actinobacteria, Bacteroidetes, Cyanobacteria, Proteobacteria and Verrucomicrobia phyla. Overall, the bacterial communities within C. tarsalis larvae were conserved and did not change across sampling dates and between two distinct plant habitats. Although Thorsellia spp. dominated mosquito gut communities, overlap of mosquito gut, plant and water-column OTUs likely reveal the effects of larval feeding. Future research will investigate the role of the key indicator groups of bacteria across the different developmental stages of this mosquito species.

Evaluation of utility monitoring and preoperational hydrothermal modeling at three nuclear power plant sites

International Nuclear Information System (INIS)

Marmer, G.J.; Policastro, A.J.

1977-01-01

This paper evaluates the preoperational hydrothermal modeling and operational monitoring carried out by utilities as three nuclear-power-plant sites using once-through cooling. Our work was part of a larger study to assess the environmental impact of operating plants for the Nuclear Regulatory Commission (NRC) and the suitability of the NRC Environmental Technical Specifications (Tech Specs) as set up for these plants. The study revealed that the plume mappings at the Kewaunee, Zion, and Quad Cities sites were generally satisfactory in terms of delineating plume size and other characteristics. Unfortunately, monitoring was not carried out during the most critical periods when largest plume size would be expected. At Kewaunee and Zion, preoperational predictions using analytical models were found to be rather poor. At Kewaunee (surface discharge), the Pritchard Model underestimated plume size in the near field, but grossly overestimated the plume's far-field extent. Moreover, lake-level variations affected plume dispersion, yet were not considered in preoperational predictions. At Zion (submerged discharge) the Pritchard Model was successful only in special, simple cases (single-unit operation, no stratification, no reversing currents, no recirculation). Due to neglect of the above-mentioned phenomena, the model underpredicted plume size. At Quad Cities (submerged discharge), the undistorted laboratory model predicted plume dispersion for low river flows. These low flow predictions appear to be reasonable extrapolations of the field data acquired at higher flows

Depth Estimation of Submerged Aquatic Vegetation in Clear Water Streams Using Low-Altitude Optical Remote Sensing.

Science.gov (United States)

Visser, Fleur; Buis, Kerst; Verschoren, Veerle; Meire, Patrick

2015-09-30

UAVs and other low-altitude remote sensing platforms are proving very useful tools for remote sensing of river systems. Currently consumer grade cameras are still the most commonly used sensors for this purpose. In particular, progress is being made to obtain river bathymetry from the optical image data collected with such cameras, using the strong attenuation of light in water. No studies have yet applied this method to map submergence depth of aquatic vegetation, which has rather different reflectance characteristics from river bed substrate. This study therefore looked at the possibilities to use the optical image data to map submerged aquatic vegetation (SAV) depth in shallow clear water streams. We first applied the Optimal Band Ratio Analysis method (OBRA) of Legleiter et al. (2009) to a dataset of spectral signatures from three macrophyte species in a clear water stream. The results showed that for each species the ratio of certain wavelengths were strongly associated with depth. A combined assessment of all species resulted in equally strong associations, indicating that the effect of spectral variation in vegetation is subsidiary to spectral variation due to depth changes. Strongest associations (R²-values ranging from 0.67 to 0.90 for different species) were found for combinations including one band in the near infrared (NIR) region between 825 and 925 nm and one band in the visible light region. Currently data of both high spatial and spectral resolution is not commonly available to apply the OBRA results directly to image data for SAV depth mapping. Instead a novel, low-cost data acquisition method was used to obtain six-band high spatial resolution image composites using a NIR sensitive DSLR camera. A field dataset of SAV submergence depths was used to develop regression models for the mapping of submergence depth from image pixel values. Band (combinations) providing the best performing models (R²-values up to 0.77) corresponded with the OBRA

Recent Advances in Ocean Nuclear Power Plants

Directory of Open Access Journals (Sweden)

Kang-Heon Lee

2015-10-01

Full Text Available In this paper, recent advances in Ocean Nuclear Power Plants (ONPPs are reviewed, including their general arrangement, design parameters, and safety features. The development of ONPP concepts have continued due to initiatives taking place in France, Russia, South Korea, and the United States. Russia’s first floating nuclear power stations utilizing the PWR technology (KLT-40S and the spar-type offshore floating nuclear power plant designed by a research group in United States are considered herein. The APR1400 and SMART mounted Gravity Based Structure (GBS-type ONPPs proposed by a research group in South Korea are also considered. In addition, a submerged-type ONPP designed by DCNS of France is taken into account. Last, issues and challenges related to ONPPs are discussed and summarized.

Biological indication with the aid of submerged vegetation - potential and limits; Bioindikation mit Hilfe Hoeherer Wasserpflanzen - Moeglichkeiten und Grenzen

Energy Technology Data Exchange (ETDEWEB)

Schuetz, W.

1991-12-31

From 1986 to 1989 the submerged vegetation of the running waters of the `Schwaebische Alb` and `Oberschwaben` were investigated. The qualitative and quantitative distribution of macrophytes depends in the first place on the occurence of extreme discharges overlaying other factors influencing the distribution of macrophytes (trophical state). The effects of increasing eutrophication can be proved, too, by reconstructing the increase resp. decrease of suitable indicator-species [Groenlandia densa (L.) FOURR.] within a larger area. The effects of water-regulation measures with ensueing eutrophication can be demonstrated in the specific case of the submerged vegetation of the Danube river and the `suedbadische Oberrheinaue`. (orig.)

Guidelines for the Acquisition of Aerial Photography for Digital Photo-Interpretation of Submerged Aquatic Vegetation (SAV)

National Research Council Canada - National Science Library

Jackson, Sam S; Graves, Mark R; Shafer, Deborah J

2006-01-01

Monitoring the success of large-scale submerged aquatic vegetation (SAV) restoration projects requires the ability to detect and map the presence or absence of SAV, as well as assess changes in SAV distributions over time...

Uptake of inorganic phosphorus by the aquatic plant Isoetes australis inhabiting oligotrophic vernal rock pools

DEFF Research Database (Denmark)

Christiansen, Nina Høj; Pulido, Cristina; Pedersen, Ole

2017-01-01

The submerged aquatic freshwater macrophyte Isoetes australis S. Williams grows in rock pools situated in south-western Australia, an environment where dissolved inorganic phosphorus (Pi) availability possibly limits growth. In contrast to the two coexisting aquatic species, Glossostigma drummundii...... experiment revealed high amounts of Pi translocation internally in the plant which seemed to go from roots and oldest leaves to younger leaves. As a result of the high root to shoot ratio, high surface area, root uptake kinetics, and sediment Pi availability, roots accounted for 87% of plant Pi uptake...

Accumulation of uranium by aquatic plants in field conditions: Prospects for phytoremediation

International Nuclear Information System (INIS)

Favas, Paulo J.C.; Pratas, João; Varun, Mayank; D'Souza, Rohan; Paul, Manoj S.

2014-01-01

A study was undertaken to determine Uranium concentrations in water and aquatic plants in the uraniferous region of Beiras, Central Portugal. Samples were collected from running water (n = 200) at places where aquatic species were observed. Plant samples were collected from 28 species of submerged, free-floating and rooted emergent plants including 2 bryophytes and 1 pteridophyte. Uranium concentrations in surface waters ranged from 0.23 to 1217 μg L −1 . The aquatic plant species studied, including several previously untested species, exhibited the ability to accumulate U in concentrations many times that of the ambient water. In general submerged plants exhibited higher U content followed by rooted emergent and free floating species. The highest U concentrations were observed in the bryophyte Fontinalis antipyretica (up to 4979 mg kg −1 ) followed by Callitriche stagnalis (1963 mg kg −1 ), Callitriche hamulata (379 mg kg −1 ), Ranunculus peltatus subsp. saniculifolius (243 mg kg −1 ), Callitriche lusitanica (218 mg kg −1 ), and Ranunculus trichophyllus (65.8 mg kg −1 ). In two out of three rooted emergent species U seemed to be preferentially partitioned in rhizome/roots with highest rhizome U content recorded in Typha latifolia (380 mg kg −1 ). Among the free-floating species, the highest U content (42.5 mg kg −1 ) was seen in Lemna minor. The bryophyte F. antipyretica and Callitrichaceae members seem to be promising candidates for the development of phytofiltration methodologies based on U accumulation, abundance and biomass production. - Highlights: • Exploration of U contamination extent in uraniferous province of Central Portugal • A group of previously untested species with the ability to accumulate U was assessed • U accumulation patterns in the species indicate their potential in bioindication and phytoremediation of U-contaminated water

Accumulation of uranium by aquatic plants in field conditions: Prospects for phytoremediation

Energy Technology Data Exchange (ETDEWEB)

Favas, Paulo J.C., E-mail: pjcf@utad.pt [School of Life Sciences and the Environment, University of Trás-os-Montes e Alto Douro, 5001-801 Vila Real (Portugal); IMAR-CMA Marine and Environmental Research Centre, Faculty of Sciences and Technology, University of Coimbra, 3001-401 Coimbra (Portugal); Pratas, João [Department of Earth Sciences, Faculty of Sciences and Technology, University of Coimbra, 3001-401 Coimbra (Portugal); IMAR-CMA Marine and Environmental Research Centre, Faculty of Sciences and Technology, University of Coimbra, 3001-401 Coimbra (Portugal); Varun, Mayank; D' Souza, Rohan; Paul, Manoj S. [Department of Botany, St. John' s College, Agra 282 002 (India)

2014-02-01

A study was undertaken to determine Uranium concentrations in water and aquatic plants in the uraniferous region of Beiras, Central Portugal. Samples were collected from running water (n = 200) at places where aquatic species were observed. Plant samples were collected from 28 species of submerged, free-floating and rooted emergent plants including 2 bryophytes and 1 pteridophyte. Uranium concentrations in surface waters ranged from 0.23 to 1217 μg L{sup −1}. The aquatic plant species studied, including several previously untested species, exhibited the ability to accumulate U in concentrations many times that of the ambient water. In general submerged plants exhibited higher U content followed by rooted emergent and free floating species. The highest U concentrations were observed in the bryophyte Fontinalis antipyretica (up to 4979 mg kg{sup −1}) followed by Callitriche stagnalis (1963 mg kg{sup −1}), Callitriche hamulata (379 mg kg{sup −1}), Ranunculus peltatus subsp. saniculifolius (243 mg kg{sup −1}), Callitriche lusitanica (218 mg kg{sup −1}), and Ranunculus trichophyllus (65.8 mg kg{sup −1}). In two out of three rooted emergent species U seemed to be preferentially partitioned in rhizome/roots with highest rhizome U content recorded in Typha latifolia (380 mg kg{sup −1}). Among the free-floating species, the highest U content (42.5 mg kg{sup −1}) was seen in Lemna minor. The bryophyte F. antipyretica and Callitrichaceae members seem to be promising candidates for the development of phytofiltration methodologies based on U accumulation, abundance and biomass production. - Highlights: • Exploration of U contamination extent in uraniferous province of Central Portugal • A group of previously untested species with the ability to accumulate U was assessed • U accumulation patterns in the species indicate their potential in bioindication and phytoremediation of U-contaminated water.

Secretome data from Trichoderma reesei and Aspergillus niger cultivated in submerged and sequential fermentation methods

Directory of Open Access Journals (Sweden)

Camila Florencio

2016-09-01

Full Text Available The cultivation procedure and the fungal strain applied for enzyme production may influence levels and profile of the proteins produced. The proteomic analysis data presented here provide critical information to compare proteins secreted by Trichoderma reesei and Aspergillus niger when cultivated through submerged and sequential fermentation processes, using steam-explosion sugarcane bagasse as inducer for enzyme production. The proteins were organized according to the families described in CAZy database as cellulases, hemicellulases, proteases/peptidases, cell-wall-protein, lipases, others (catalase, esterase, etc., glycoside hydrolases families, predicted and hypothetical proteins. Further detailed analysis of this data is provided in “Secretome analysis of Trichoderma reesei and Aspergillus niger cultivated by submerged and sequential fermentation process: enzyme production for sugarcane bagasse hydrolysis” C. Florencio, F.M. Cunha, A.C Badino, C.S. Farinas, E. Ximenes, M.R. Ladisch (2016 [1]. Keywords: Tricoderma reesei, Aspergillus Niger, Enzyme Production, Secretome

Mitigation of severe accidents in Swedish nuclear power plants

International Nuclear Information System (INIS)

Soederman, E.

1987-01-01

Sweden is the first country to build filtered venting systems, the first one became operable at Barsebaeck nuclear power plant in 1985. In new concepts, now being installed in Sweden, an enhanced containment spray system is the basic element and the filtered venting is only the secondary mitigating system. The filter is a new design, a submerged multi venturi scrubber. The Swedish strategy has been built on three basics: improved knowledge through research; containment integrity through mitigating systems; and accident management to prevent severe accidents. 2 figs

Submerged pedology: the soils of minor islands in the Venice lagoon

Directory of Open Access Journals (Sweden)

Mohammad Washa

2015-12-01

Full Text Available Minor islands of the Venice lagoon are part of a delicate ecosystem, with equilibrium that depends on multiple factors deriving from both the aqueous and the terrestrial compartment, and represent useful indicators of the lagoon ecosystem status. Over centuries, some islands emerged, some others disappeared, others are being submerged in consequence of sea level rise, or are dismantled by marine erosion. Ecological survey and soil sampling evidenced rather homogeneous environment and soil characters, likely due to the same genesis from HTM during centuries, and to environmental conditions such as moisture and brackish groundwater. Four of the examined soils are Inceptisols, while the others present limited horizon differentiation, and are Entisols. All the profiles reflect udic or aquic conditions, and some of them are submerged for most time. Most soils are moderately alkaline (7.9 250 g/kg; organic carbon content at surface is within the normal range (8 17 g/kg and carbonates. Moreover, the textural class is generally silty-loam with increasing clay content with depth. Currently, the soils examined present hydromorphic pedofeatures, which are the result of the most important pedogenic process in the lagoon. Alternating reduction/oxidation processes would increase as a consequence of sea level rise, determining reducing conditions at bottom, and conversely enhancing salt concentration uppermost, with negative consequences for both pedogenic evolution and vegetation survival.

Ethylene, nitric oxide and haemoglobins in plant tolerance to flooding

DEFF Research Database (Denmark)

Mur, Luis A J; Gupta, Kapuganti J; Chakraborty, U

2015-01-01

-tolerant species Rumex palustris and the model plant Arabidopsis thaliana have been extensively exploited to reveal some key molecular events. Our groups have recently demonstrated that nitric oxide (NO) triggers the biosynthesis of ethylene during stress and that NO plays key roles in PCD and the hyponastic......As much as 12% of the world's soils may suffer excess water so that flooding is a major limiting factor on crop production in many areas. Plants attempt to deal with submergence by forming root aerenchyma to facilitate oxygen diffusion from the shoot to the root, initiating a hyponastic response....... This chapter will detail our understanding of the roles of ethylene, NO and haemoglobin in flooding stress....

Submerged-arc wire electrodes with nickel-plated surfaces

International Nuclear Information System (INIS)

Hagen, H. vom.

1976-01-01

The article reports on the development of SANWELD welding rods at GARHYTTAN's which is a wire free of impurities, copper, and hydrogen with a nickel surface. It is producted according to the SANBOND process. The wire has an optimum of mechanical quality grades depending on the powder used for welding, especially an improvement of notch impact strength. The elongation, especially the long-time values, are improved, hydrogen cracks are excluded depending on the correct powder or protective gas, and the low-temparature values are improved. An attendant phenomenon, which is not unimportant, is that the wires are practically corrosion-resistant in the non-welded state. The wire is suitable for submerged-arc welding in steam boilers and pressure vessels. (IHoe) [de

The use of alpha-methyl-D-glucoside, a synthetic analogue of maltose, as inducer of amylase by Aspergillus sp in solid-state and submerged fermentations

Directory of Open Access Journals (Sweden)

Fabiana G. Moreira

2001-03-01

Full Text Available The use of a methyl-D-glucoside (alphaMG, a synthetic analogue of maltose, as carbon source and inducer of amylase synthesis to several species of Aspergillus was studied in submerged and solid-state fermentations. Among a group of ten species, A. tamarii, A. fumigatus and A. flavus were able to produce biomass and high specific amylolytic activity in submerged cultures containing alphaMG as the only carbon source. In solid state fermentation, the enrichment of basal wheat bran or corn cob medium with alphaMG increased up to 3 times the production of amylases. In both submerged and solid state fermentations, alphaMG was more effective inducer of amylases than maltose and starch.

The use of a-methyl-D-glucoside, a synthetic analogue of maltose, as inducer of amylase by Aspergillus sp in solid-state and submerged fermentations

Directory of Open Access Journals (Sweden)

Moreira Fabiana G.

2001-01-01

Full Text Available The use of a methyl-D-glucoside (alphaMG, a synthetic analogue of maltose, as carbon source and inducer of amylase synthesis to several species of Aspergillus was studied in submerged and solid-state fermentations. Among a group of ten species, A. tamarii, A. fumigatus and A. flavus were able to produce biomass and high specific amylolytic activity in submerged cultures containing alphaMG as the only carbon source. In solid state fermentation, the enrichment of basal wheat bran or corn cob medium with alphaMG increased up to 3 times the production of amylases. In both submerged and solid state fermentations, alphaMG was more effective inducer of amylases than maltose and starch.

UV mutagenesis of aspergillus niger for enzyme production in submerged fermentation

International Nuclear Information System (INIS)

Irfan, M.; Syed, Q.; Javed, J.

2011-01-01

The present study was conducted to improve the enzyme production from Aspergillus niger using UV mutation. Submerged fermentation was carried out in 250 ml Erlenmeyer flask using Vogel's media at 30 deg. C for six days. Results of this study revealed that UV-mutation enhanced CM Case activity up to two times while FPase activity up to three times as compared to the parental strain. For avicelase, xylanase and fungal biomass production, UV radiation has slight effect as compared to parental strain. (author)

3-D flow and scour near a submerged wing dike: ADCP measurements on the Missouri River

Science.gov (United States)

Jamieson, E.C.; Rennie, C.D.; Jacobson, R.B.; Townsend, R.D.

2011-01-01

Detailed mapping of bathymetry and three-dimensional water velocities using a boat-mounted single-beam sonar and acoustic Doppler current profiler (ADCP) was carried out in the vicinity of two submerged wing dikes located in the Lower Missouri River near Columbia, Missouri. During high spring flows the wing dikes become submerged, creating a unique combination of vertical flow separation and overtopping (plunging) flow conditions, causing large-scale three-dimensional turbulent flow structures to form. On three different days and for a range of discharges, sampling transects at 5 and 20 m spacing were completed, covering the area adjacent to and upstream and downstream from two different wing dikes. The objectives of this research are to evaluate whether an ADCP can identify and measure large-scale flow features such as recirculating flow and vortex shedding that develop in the vicinity of a submerged wing dike; and whether or not moving-boat (single-transect) data are sufficient for resolving complex three-dimensional flow fields. Results indicate that spatial averaging from multiple nearby single transects may be more representative of an inherently complex (temporally and spatially variable) three-dimensional flow field than repeated single transects. Results also indicate a correspondence between the location of calculated vortex cores (resolved from the interpolated three-dimensional flow field) and the nearby scour holes, providing new insight into the connections between vertically oriented coherent structures and local scour, with the unique perspective of flow and morphology in a large river.

Vertical Gradient Freezing Using Submerged Heater Growth With Rotation and With Weak Magnetic and Electric Fields

National Research Council Canada - National Science Library

Bliss, D. F; Holmes, A. M; Wang, X; Ma, N; Iseler, G. W

2005-01-01

...) method utilizing a submerged heater. Electromagnetic stirring can be induced in the gallium-antimonide melt just above the crystal growth interface by applying a weak radial electric current in the melt together with a weak axial magnetic field...

Will heavy metals in the soils of newly submerged areas threaten the water quality of Danjiangkou Reservoir, China?

Science.gov (United States)

Song, Zhixin; Shan, Baoqing; Tang, Wenzhong; Zhang, Chao

2017-10-01

Soil heavy metal contents were measured in newly submerged areas of the Danjiangkou Reservoir, China. We aimed to determine the heavy metal distribution in this area and the associated ecological risk. Most of these heavy metal contents (except Pb and Mn) suggest enrichment compared with the background values of soils from Henan Province, especially As and Cd with mean geo-accumulation index (I geo ) values of 0.84 and 0.54. The spatial analysis results indicated that the highest heavy metal contents were distributed in the arable soils above 160m elevation, whereas low heavy metal contents were observed under other land-use types above 160m elevation. According to I geo and EF values, Cd was the major heavy metal contaminant in the newly submerged area, Cr, Pb and Mn mainly originated from natural geochemical sources. In contrast, Ni, Cd, As, Cu, and Zn mainly originated from anthropogenic sources. Evaluation using the potential ecological risk (PER) method indicated that PER of individual elements were low in the studied soils, and the comprehensive PER index was at a moderate level, indicating heavy metals in the soils of newly submerged areas may not threaten the water quality of Danjiangkou Reservoir, especially in winter. Copyright © 2017 Elsevier Inc. All rights reserved.

Methane oxidation associated to submerged brown-mosses buffers methane emissions from Siberian polygonal peatlands

Science.gov (United States)

Liebner, Susanne; Zeyer, Josef; Knoblauch, Christian

2010-05-01

Circumpolar peatlands store roughly 18 % of the globally stored carbon in soils [based on 1, 2]. Also, northern wetlands and tundra are a net source of methane (CH4), an effective greenhouse gas (GHG), with an estimated annual CH4 release of 7.2% [3] or 8.1% [4] of the global total CH4 emission. Although it is definite that Arctic tundra significantly contributes to the global methane emissions in general, regional variations in GHG fluxes are enormous. CH4 fluxes of polygonal tundra within the Siberian Lena Delta, for example, were reported to be low [5, 6], particularly at open water polygonal ponds and small lakes [7] which make up around 10 % of the delta's surface. Low methane emissions from polygonal ponds oppose that Arctic permafrost thaw ponds are generally known to emit large amounts of CH4 [8]. Combining tools of biogeochemistry and molecular microbiology, we identified sinks of CH4 in polygonal ponds from the Lena Delta that were not considered so far in GHG studies from Arctic wetlands. Pore water CH4 profiling in polygonal ponds on Samoylov, a small island in the central part of the Lena Delta, revealed a pronounced zone of CH4 oxidation near the vegetation surface in submerged layers of brown-mosses. Here, potential CH4 oxidation was an order of magnitude higher than in non-submerged mosses and in adjacent bulk soil. We could additionally show that this moss associated methane oxidation (MAMO) is hampered when exposure of light is prevented. Shading of plots with submerged Scorpidium scorpioides inhibited MAMO leading to higher CH4 concentrations and an increase in CH4 fluxes by a factor of ~13. Compared to non-submerged mosses, the submerged mosses also showed significantly lower δ13C values indicating that they use carbon dioxide derived from methane oxidation for photosynthesis. Applying stable isotope probing of DNA, type II methanotrophs were identified to be responsible for the oxidation of CH4 in the submerged Scorpidium scorpioides. Our

Medium selection for exopolysaccharide and biomass production in submerged cultures of culinary-medicinal mushrooms from Turkey

NARCIS (Netherlands)

Kizilcik, M.; Yamaç, M.; Griensven, van L.J.L.D.

2010-01-01

The present study investigates the exopolysaccharide (EPS) and biomass production of 18 strains of 15 species of culinary-medicinal higher Basidiomycetes in submerged culture under four different media. Gloeophyllum abietinum and Schizophyllum commune produced the highest EPS and biomass

Offshore atomic power plants

International Nuclear Information System (INIS)

Anon.

1975-01-01

Various merits of offshore atomic power plants are illustrated, and their systems are assessed. The planning of the offshore atomic power plants in USA is reviewed, and the construction costs of the offshore plant in Japan were estimated. Air pollution problem may be solved by the offshore atomic power plants remarkably. Deep water at low temperature may be advantageously used as cooling water for condensers. Marine resources may be bred by building artificial habitats and by providing spring-up equipments. In the case of floating plants, the plant design can be standardized so that the construction costs may be reduced. The offshore plants can be classified into three systems, namely artificial island system, floating system and sea bottom-based system. The island system may be realized with the present level of civil engineering, but requires the development of technology for the resistance of base against earthquake and its calculation means. The floating system may be constructed with conventional power plant engineering and shipbuilding engineering, but the aseismatic stability of breakwater may be a problem to be solved. Deep water floating system and deep water submerging system are conceivable, but its realization may be difficult. The sea bottom-based system with large caissons can be realized by the present civil engineering, but the construction of the caissons, stability against earthquake and resistance to waves may be problems to be solved. The technical prediction and assessment of new plant sites for nuclear power plants have been reported by Science and Technology Agency in 1974. The construction costs of an offshore plant has been estimated by the Ministry of International Trade and Industry to be yen71,026/kW as of 1985. (Iwakiri, K.)

Physiological studies on photochemical oxidant injury in rice plants. III. Relationship between abscisic acid (ABA) and water metabolism in water-stressed rice plants

Energy Technology Data Exchange (ETDEWEB)

Jeong, Y.H.; Ota, Y.

1981-12-01

Several experiments were carried out to determine the effects of exogenously applied ABA on water metabolism, and to clarify the endogenous ABA relationships in ozone-sensitivity under different soil water content in rice plants. The rice plants were cultivated in soil with 60, 80, and 100% of maximum water holding capacity and under submerged condition. The results of the experiments were as follows: ozone injury was reduced with increasing ABA content of which production was increased under water stress conditions. Under water stressed conditions, the rate of water loss was decreased with increasing concentration of ABA applied exogenously. It may be assumed that the ozone-sensitivity is closely related to the stomatal closure caused by the increased ABA content due to water stress. 5 references, 4 tables.

Aspergillus oryzae in solid-state and submerged fermentations: Progress report on a multi-disciplinary project

NARCIS (Netherlands)

Biesebeke, R. te; Ruijter, G.; Rahardjo, Y.S.P.; Hoogschagen, M.J.; Heerikhuisen, M.; Levin, A.; Driel, K.G.A. van; Schutyser, M.A.I.; Dijksterhuis, J.; Zhu, Y.; Weber, F.J.; Vos, W.M. de; Hondel, K.A.M.J.J. van den; Rinzema, A.; Punt, P.J.

2002-01-01

We report the progress of a multi-disciplinary research project on solid-state fermentation (SSF) of the filamentous fungus Aspergillus oryzae. The molecular and physiological aspects of the fungus in submerged fermentation (SmF) and SSF are compared and we observe a number of differences correlated

Aspergillus oryzae in solid-state and submerged fermentations. Progress report on a multi-disciplinary project

NARCIS (Netherlands)

te Biesebeke, Rob; Ruijter, George; Rahardjo, Yovita S P; Hoogschagen, Marisca J; Heerikhuisen, Margreet; Levin, Ana; van Driel, Kenneth G A; Schutyser, Maarten A I; Dijksterhuis, Jan; Zhu, Yang; Weber, Frans J; de Vos, Willem M; van den Hondel, Kees A M J J; Rinzema, Arjen; Punt, Peter J

We report the progress of a multi-disciplinary research project on solid-state fermentation (SSF) of the filamentous fungus Aspergillus oryzae. The molecular and physiological aspects of the fungus in submerged fermentation (SmF) and SSF are compared and we observe a number of differences correlated

Aspergillus oryzae in solid-state and submerged fermentations. Progress report on a multi-disciplinary project

NARCIS (Netherlands)

Biesebeke, te R.; Ruijter, G.; Rahardjo, Y.S.P.; Hoogschagen, M.J.; Heerikhuisen, M.; Levin, A.; Driel, van K.G.A.; Schutyser, M.A.I.; Dijksterhuis, J.; Yang Zhu, Yang; Weber, F.J.; Vos, de W.M.; Hondel, van den K.A.; Rinzema, A.; Punt, P.J.

2002-01-01

We report the progress of a multi-disciplinary research project on solid-state fermentation (SSF) of the filamentous fungus Aspergillus oryzae. The molecular and physiological aspects of the fungus in submerged fermentation (SmF) and SSF are compared and we observe a number of differences correlated

Advances in submerged arc, narrow-gap welding with strip electrodes and thin, dual-wire electrodes

International Nuclear Information System (INIS)

Nies, H.

1990-01-01

Container and tank construction for nuclear installations traditionally is one of the major applications of narrow-gap welding with the submerged arc technique. This type of welding presents one problem, namely to completely and reliably remove the welding slag from the deep and narrow gap. The research report in hand explains the variants of welding techniques that have been tested and describes the results obtained, which primarily are reduced occurrence of faults, i.e. enhanced reliability, and better welding economy. As an alternative to welding with thick wire electrodes, which is the standard method for the applications under review, a new technique has been conceived and extensively tested, which uses thin strip electrodes at longitudinal position in the gap. This submerged arc, dual-wire technique with thin electrodes is characterised by a significantly higher thermal efficiency compared to welding with thick wires, so that the same energy input yields better efficiency of metal deposition. (orig./MM) [de

Submerged Glow-Discharge Plasma: An Economical Approach to Convert Construction Scrap Metal into Nanomaterials

Science.gov (United States)

Yek, Peter Nai Yuh; Rafiq Mirza Julaihi, Muhammad; Shahril Osman, Mohammad; Tiong, Tung Chuan; Lee, Wak Ha; Leing Lee, Chern

2018-03-01

Submerged glow-discharge plasma (SGDP) is relatively new among the various methods available for nanomaterials synthesis (NMs) techniques. This method allows great control over the production cost of nanomaterials synthesis. A lab-scale batch type SDGP technology has been constructed to produce nanomaterials and investigate the inter-relationship between plasma excitation voltages, electrodes submerged areas and electrolyte concentration. Metal oxide nanospheres has been synthesised from different electrolyte concentrations (1M-0.001M) and characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). As the major results showed that the nanospheres are uniformly spherical with diameter size distribution are between 100 nm - 2μm. EDS analysis shown the nano-Iron Oxide have been formed. Scrap metal initially showed around 6.45% and 93.55% of Carbon and Iron composition respectively. After SGDP process to the scrap metal, Carbon content has increased to 34-35% and Iron content has reduced to around 15-40%. EDS results also shown the higher percentage of Iron amount has remained with lower electrolyte concentration and Current is proportionally related to submersion area of cathode.

Grey water treatment by a continuous process of an electrocoagulation unit and a submerged membrane bioreactor system

KAUST Repository

Bani-Melhem, Khalid; Smith, Edward

2012-01-01

This paper presents the performance of an integrated process consisting of an electro-coagulation (EC) unit and a submerged membrane bioreactor (SMBR) technology for grey water treatment. For comparison purposes, another SMBR process without

Measuring air layer volumes retained by submerged floating-ferns Salvinia and biomimetic superhydrophobic surfaces

Directory of Open Access Journals (Sweden)

Matthias J. Mayser

2014-06-01

Full Text Available Some plants and animals feature superhydrophobic surfaces capable of retaining a layer of air when submerged under water. Long-term air retaining surfaces (Salvinia-effect are of high interest for biomimetic applications like drag reduction in ship coatings of up to 30%. Here we present a novel method for measuring air volumes and air loss under water. We recorded the buoyancy force of the air layer on leaf surfaces of four different Salvinia species and on one biomimetic surface using a highly sensitive custom made strain gauge force transducer setup. The volume of air held by a surface was quantified by comparing the buoyancy force of the specimen with and then without an air layer. Air volumes retained by the Salvinia-surfaces ranged between 0.15 and 1 L/m2 depending on differences in surface architecture. We verified the precision of the method by comparing the measured air volumes with theoretical volume calculations and could find a good agreement between both values. In this context we present techniques to calculate air volumes on surfaces with complex microstructures. The introduced method also allows to measure decrease or increase of air layers with high accuracy in real-time to understand dynamic processes.

EAARL-B coastal topography: Fire Island, New York, pre-Hurricane Sandy, 2012: seamless (bare earth and submerged)

Science.gov (United States)

Wright, C. Wayne; Kranenburg, Christine J.; Klipp, Emily S.; Troche, Rodolfo J.; Fredericks, Alexandra M.; Masessa, Melanie L.; Nagle, David B.

2014-01-01

These remotely sensed, geographically referenced elevation measurements of lidar-derived seamless (bare-earth and submerged) topography datasets were produced by the U.S. Geological Survey (USGS), St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida.

Modeling of plant in vitro cultures: overview and estimation of biotechnological processes.

Science.gov (United States)

Maschke, Rüdiger W; Geipel, Katja; Bley, Thomas

2015-01-01

Plant cell and tissue cultivations are of growing interest for the production of structurally complex and expensive plant-derived products, especially in pharmaceutical production. Problems with up-scaling, low yields, and high-priced process conditions result in an increased demand for models to provide comprehension, simulation, and optimization of production processes. In the last 25 years, many models have evolved in plant biotechnology; the majority of them are specialized models for a few selected products or nutritional conditions. In this article we review, delineate, and discuss the concepts and characteristics of the most commonly used models. Therefore, the authors focus on models for plant suspension and submerged hairy root cultures. The article includes a short overview of modeling and mathematics and integrated parameters, as well as the application scope for each model. The review is meant to help researchers better understand and utilize the numerous models published for plant cultures, and to select the most suitable model for their purposes. © 2014 Wiley Periodicals, Inc.

Generic phylogeny, historical biogeography and character evolution of the cosmopolitan aquatic plant family Hydrocharitaceae

Directory of Open Access Journals (Sweden)

Chen Ling-Yun

2012-03-01

Full Text Available Abstract Background Hydrocharitaceae is a fully aquatic monocot family, consists of 18 genera with approximately 120 species. The family includes both fresh and marine aquatics and exhibits great diversity in form and habit including annual and perennial life histories; submersed, partially submersed and floating leaf habits and linear to orbicular leaf shapes. The family has a cosmopolitan distribution and is well represented in the Tertiary fossil record in Europe. At present, the historical biogeography of the family is not well understood and the generic relationships remain controversial. In this study we investigated the phylogeny and biogeography of Hydrocharitaceae by integrating fossils and DNA sequences from eight genes. We also conducted ancestral state reconstruction for three morphological characters. Results Phylogenetic analyses produced a phylogeny with most branches strongly supported by bootstrap values greater than 95 and Bayesian posterior probability values of 1.0. Stratiotes is the first diverging lineage with the remaining genera in two clades, one clade consists of Lagarosiphon, Ottelia, Blyxa, Apalanthe, Elodea and Egeria; and the other consists of Hydrocharis-Limnobium, Thalassia, Enhalus, Halophila, Najas, Hydrilla, Vallisneria, Nechamandra and Maidenia. Biogeographic analyses (DIVA, Mesquite and divergence time estimates (BEAST resolved the most recent common ancestor of Hydrocharitaceae as being in Asia during the Late Cretaceous and Palaeocene (54.7-72.6 Ma. Dispersals (including long-distance dispersal and migrations through Tethys seaway and land bridges probably played major roles in the intercontinental distribution of this family. Ancestral state reconstruction suggested that in Hydrocharitaceae evolution of dioecy is bidirectional, viz., from dioecy to hermaphroditism, and from hermaphroditism to dioecy, and that the aerial-submerged leaf habit and short-linear leaf shape are the ancestral states. Conclusions

Generic phylogeny, historical biogeography and character evolution of the cosmopolitan aquatic plant family Hydrocharitaceae.

Science.gov (United States)

Chen, Ling-Yun; Chen, Jin-Ming; Gituru, Robert Wahiti; Wang, Qing-Feng

2012-03-10

Hydrocharitaceae is a fully aquatic monocot family, consists of 18 genera with approximately 120 species. The family includes both fresh and marine aquatics and exhibits great diversity in form and habit including annual and perennial life histories; submersed, partially submersed and floating leaf habits and linear to orbicular leaf shapes. The family has a cosmopolitan distribution and is well represented in the Tertiary fossil record in Europe. At present, the historical biogeography of the family is not well understood and the generic relationships remain controversial. In this study we investigated the phylogeny and biogeography of Hydrocharitaceae by integrating fossils and DNA sequences from eight genes. We also conducted ancestral state reconstruction for three morphological characters. Phylogenetic analyses produced a phylogeny with most branches strongly supported by bootstrap values greater than 95 and Bayesian posterior probability values of 1.0. Stratiotes is the first diverging lineage with the remaining genera in two clades, one clade consists of Lagarosiphon, Ottelia, Blyxa, Apalanthe, Elodea and Egeria; and the other consists of Hydrocharis-Limnobium, Thalassia, Enhalus, Halophila, Najas, Hydrilla, Vallisneria, Nechamandra and Maidenia. Biogeographic analyses (DIVA, Mesquite) and divergence time estimates (BEAST) resolved the most recent common ancestor of Hydrocharitaceae as being in Asia during the Late Cretaceous and Palaeocene (54.7-72.6 Ma). Dispersals (including long-distance dispersal and migrations through Tethys seaway and land bridges) probably played major roles in the intercontinental distribution of this family. Ancestral state reconstruction suggested that in Hydrocharitaceae evolution of dioecy is bidirectional, viz., from dioecy to hermaphroditism, and from hermaphroditism to dioecy, and that the aerial-submerged leaf habit and short-linear leaf shape are the ancestral states. Our study has shed light on the previously controversial

Medium pH in submerged cultivation modulates differences in the intracellular protein profile of Fusarium oxysporum.

Science.gov (United States)

da Rosa-Garzon, Nathália Gonsales; Laure, Hélen Julie; Souza-Motta, Cristina Maria de; Rosa, José César; Cabral, Hamilton

2017-08-09

Fusarium oxysporum is a filamentous fungus that damages a wide range of plants and thus causes severe crop losses. In fungal pathogens, the genes and proteins involved in virulence are known to be controlled by environmental pH. Here, we report the influence of culture-medium pH (5, 6, 7, and 8) on the production of degradative enzymes involved in the pathogenesis of F. oxysporum URM 7401 and on the 2D-electrophoresis profile of intracellular proteins in this fungus. F. oxysporum URM 7401 was grown in acidic, neutral, and alkaline culture media in a submerged bioprocess. After 96 hr, the crude extract was processed to enzyme activity assays, while the intracellular proteins were obtained from mycelium and analyzed using 2D electrophoresis and mass spectrometry. We note that the diversity of secreted enzymes was changed quantitatively in different culture-medium pH. Also, the highest accumulated biomass and the intracellular protein profile of F. oxysporum URM 7401 indicate an increase in metabolism in neutral-alkaline conditions. The differential profiles of secreted enzymes and intracellular proteins under the evaluated conditions indicate that the global protein content in F. oxysporum URM 7401 is modulated by extracellular pH.

Finite element modelling of electric currents in AC submerged arc furnaces

CSIR Research Space (South Africa)

Mc Dougall, I

2007-01-01

Full Text Available and the power ratings is not a hindrance. 2. MATHEMATICAL FORMULATION As the frequency of the current is low, the quasi-static form of Maxwell’s equations is solved. (1) (2) (3) (4) where E denotes the electric field intensity, H the magnetic field... of Electric Currents in AC Submerged Arc Furnaces 637 REFERENCES [1] Bermudez, A., Muniz, M.C., Pena, F. , Bullon, J., “ Numerical Computation of the Electromagnetic Field in the Electrodes of a Three-Phase Arc Furnace”, Int. Jnl for Numerical Methods...

Single-walled nanohorns and other nanocarbons generated by submerged arc discharge between carbon electrodes in liquid argon and other media

International Nuclear Information System (INIS)

Vasu, K; Pramoda, K; Govindaraj, A; Rao, C N R; Moses, K

2014-01-01

Arc discharge between two graphite electrodes submerged in different liquid media yields various dimensional nanocarbon structures such as 1D carbon nanotubes and 2D graphene. Single-walled carbon nanohorns (SWNHs) prepared by submerged arc discharge in liquid nitrogen medium are found to have nitrogen impurities. Here, we report the structure and properties of pure and nitrogen-doped SWNHs obtained by submerged arc discharge in a liquid argon medium. The absence of an XPS N 1s signal, which is present in nanohorns obtained in liquid nitrogen, indicate that the nanohorns are free from nitrogen impurities. Raman spectra show a strong defect-induced D band and current–voltage characteristics show a slight nonlinear behavior. N 2 adsorption of pure SWNHs shows type-IV isotherms with a surface area of 300 m 2 g −1 . Adsorption of CO 2 and H 2 in pure SWNHs has also been measured. Arc discharge in other liquid media such as water, ethanol, dimethylformamide (DMF), n-methyl pyrrolidone (NMP), formamide, benzene, heptane and acetone yields different nanocarbon structures including multi-walled carbon nanotubes (MWNTs), few-layer graphene, carbon onions and carbon nanoparticles. (papers)

Clinical and Radiologic Outcomes of Submerged and Nonsubmerged Bone-Level Implants with Internal Hexagonal Connections in Immediate Implantation: A 5-Year Retrospective Study.

Science.gov (United States)

Wu, Shiyu; Wu, Xiayi; Shrestha, Rachana; Lin, Jinying; Feng, Zhicai; Liu, Yudong; Shi, Yunlin; Huang, Baoxin; Li, Zhipeng; Liu, Quan; Zhang, Xiaocong; Hu, Mingxuan; Chen, Zhuofan

2018-02-01

To evaluate the 5-year clinical and radiologic outcome of immediate implantation using submerged and nonsubmerged techniques with bone-level implants and internal hexagonal connections and the effects of potential influencing factors. A total of 114 bone-level implants (XiVE S plus) with internal hexagonal connections inserted into 72 patients were included. Patients were followed up for 5 years. A t-test was used to statistically evaluate the marginal bone loss between the submerged and nonsubmerged groups. The cumulative survival rate (CSR) was calculated according to the life table method and illustrated with Kaplan-Meier survival curves. Comparisons of the CSR between healing protocols, guided bone regeneration, implants with different sites, lengths, and diameters were performed using log-rank tests. The 5-year cumulative implant survival rates with submerged and nonsubmerged healing were 94% and 96%, respectively. No statistically significant differences in terms of marginal bone loss, healing protocol, application of guided bone regeneration, implant site, or length were observed. High CSRs and good marginal bone levels were achieved 5 years after immediate implantation of bone-level implants with internal hexagonal connections using both the submerged and nonsubmerged techniques. Factors such as implant length, site, and application of guided bone regeneration did not have an impact on the long-term success of the implants. © 2017 by the American College of Prosthodontists.

Submerged fermentation of Lactobacillus rhamnosus YS9 for γ-aminobutyric acid (GABA) production

OpenAIRE

Lin,Qian

2013-01-01

γ-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter in central nervous system, and its application in drugs and functional foods has attracted great attention. To enhance production of y-aminobutyric acid, Lactobacillus rhamnosus YS9, a strain isolated from Chinese traditional fermented food pickled vegetable, was grown under submerged fermentation. Its cultivation conditions were investigated. When culture pH condition was adjusted to the optimal pH of glutamate decarboxyl...

Comparative study of submerged and surface culture acetification process for orange vinegar.

Science.gov (United States)

Cejudo-Bastante, Cristina; Durán-Guerrero, Enrique; García-Barroso, Carmelo; Castro-Mejías, Remedios

2018-02-01

The two main acetification methodologies generally employed in the production of vinegar (surface and submerged cultures) were studied and compared for the production of orange vinegar. Polyphenols (UPLC/DAD) and volatiles compounds (SBSE-GC/MS) were considered as the main variables in the comparative study. Sensory characteristics of the obtained vinegars were also evaluated. Seventeen polyphenols and 24 volatile compounds were determined in the samples during both acetification processes. For phenolic compounds, analysis of variance showed significant higher concentrations when surface culture acetification was employed. However, for the majority of volatile compounds higher contents were observed for submerged culture acetification process, and it was also reflected in the sensory analysis, presenting higher scores for the different descriptors. Multivariate statistical analysis such as principal component analysis demonstrated the possibility of discriminating the samples regarding the type of acetification process. Polyphenols such as apigenin derivative or ferulic acid and volatile compounds such as 4-vinylguaiacol, decanoic acid, nootkatone, trans-geraniol, β-citronellol or α-terpineol, among others, were those compounds that contributed more to the discrimination of the samples. The acetification process employed in the production of orange vinegar has been demonstrated to be very significant for the final characteristics of the vinegar obtained. So it must be carefully controlled to obtain high quality products. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Accumulation of americium-241 in the biomass of aquatic plants of the Yenisei river: experimental study

International Nuclear Information System (INIS)

Zotina, T.A.; Bolsunovsky, A.Y.A.; Bondareva, L.G.

2004-01-01

Due to the operation of the Mining-and-Chemical Combine (Krasnoyarsk-26), which has been manufacturing weapons-grade plutonium for several decades, the Yenisei River is contaminated with transuranic elements (including 241 Am). 241 Am was found in the riverside soil, sediment and in the biomass of aquatic plants (Bolsunovsky et al., 1999, 2002). Aquatic plants are an important link in the migration of radionuclides in an aquatic ecosystem. In laboratory experiments, we investigated accumulation of 241 Am by the submerged macrophyte from the Yenisei River: the pond weed (Elodea canadensis) and the aquatic moss (Fontinalis antipyretica), and release of 241 Am from the biomass. The content of 241 Am was measured on a Canberra (USA) gamma-spectrometer. The experiments showed that specific accumulation and concentration factors of 241 Am in the plants were in inverse proportion to their biomass. We obtained new data on release of 241 Am from the biomass of macrophyte. Americium-241 was more firmly fixed in the biomass of the aquatic moss. In 12 months, the biomass of the aquatic moss released about 30% of the initial americium activity into the water. To compare, the biomass of the pond weed released into the water medium up to 64% of the initial 241 Am activity in 1.5 4 months. The release rate was dependent on the decomposition rate of the plant biomass. The experiments showed that submerged macrophyte of the Yenisei River can accumulate considerable activities of 241 Am and retain americium for long periods of time in biomass. (author)

Biomass production of pleurotus sajor-caju by submerged culture fermentation

International Nuclear Information System (INIS)

Kausar, T.; Nasreen, Z.; Nadeem, M.; Baig, S.

2006-01-01

The effect of different carbon sources, namely, sawdust and powder of agro wastes (as such, or water soluble extracts), and inorganic/natural nitrogen sources on the biomass production of Pleurotus sajor-caju by submerged culture fermentation was studied. Supplementation of the fermentation medium with 2% molasses, 2% wheat spike powder, extract of 2% wheat spike powder, and com gluten meal resulted in 12.85, 10.85, 12.35 and 13.92 g/sub l/ biomass production of P. sajor-caju, respectively. The fungal hyphae biomass contained 8.28% moisture, 21.18% crude protein, 1.55% fat, 3.59% ash, 2.32% crude fibre, and 63.48% nitrogen-free extract. (author)

Bisphenol A Removal by Submerged Macrophytes and the Contribution of Epiphytic Microorganisms to the Removal Process.

Science.gov (United States)

Zhang, Guosen; Wang, Yu; Jiang, Jinhui; Yang, Shao

2017-06-01

Bisphenol A (BPA), a typical endocrine disruptor, has been found in global aquatic environments, causing great concern. The capabilities of five common submerged macrophytes to remove BPA from water and the contributions of epiphytic microorganisms were investigated. Macrophytes removed 62%-100% of total BPA (5 mg/L) over 12 days; much higher rates than that observed in the control (2%, F = 261.511, p = 0.000). Ceratophyllum demersum was the most efficient species. C. demersum samples from lakes with different water qualities showed no significant differences in BPA removal rates. Moreover, removal, inhibition or re-colonization of epiphytic microorganisms did not significantly change the BPA removal rates of C. demersum. Therefore, the contributions of epiphytic microorganisms to the BPA removal process were negligible. The rate of BPA accumulation in C. demersum was 0.1%, indicating that BPA was mainly biodegraded by the macrophyte. Hence, submerged macrophytes, rather than epiphytic microorganisms, substantially contribute to the biodegradation of BPA in water.

Nitrifying Community Analysis in a Single Submerged Attached-Growth Bioreactor for Treatment of High-Ammonia Waste Stream

DEFF Research Database (Denmark)

Gu, April Z.; Pedros, Philip B; Kristiansen, Anja

2007-01-01

This study investigated the nitrifying community structure in a single-stage submerged attached-growth bioreactor (SAGB) that successfully achieved stable nitrogen removal over nitrite of a high-strength ammonia wastewater. The reactor was operated with intermittent aeration and external carbon...

Microbial production of four biodegradable siderophores under submerged fermentation.

Science.gov (United States)

Fazary, Ahmed E; Al-Shihri, Ayed S; Alfaifi, Mohammad Y; Saleh, Kamel A; Alshehri, Mohammed A; Elbehairi, Serag Eldin I; Ju, Yi-Hsu

2016-07-01

Four siderophore analogues were isolated and purified from Escherichia coli, Bacillus spp. ST13, and Streptomyces pilosus microorganisms under some specific submerged fermentation conditions. In order to evaluate the highest production of this siderophore analogues through the growth, a rapid spectrophotometric screening semi-quantitative method was used, in which interestingly the analogues were isolated in its own form not its iron chelate. After chromatographic separation, the chemical structures of the isolated and purified siderophores were illustrated using detailed spectroscopic techniques. The biodegradation studies were done on that four novel isolated and purified siderophores following OECD protocols. In addition, the bioactivities of these siderophores and their iron complexes were examined and evaluated. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of submerged, freshwater aquatic macrophytes and littoral sediments on pan evaporation in the Lake Balaton region, Hungary

Science.gov (United States)

Anda, A.; Simon, B.; Soos, G.; Teixeira da Silva, J. A.; Kucserka, T.

2016-11-01

The evaporation (Ep) of a US Class A pan (C) with submerged, freshwater aquatic macrophytes (Potamogeton perfoliatus, Myriophyllum spicatum and Najas marina), hereafter macrophytes (Ps) and a sediment-covered bottom (S) was measured in Hungary during 2014-2015 using reference E of Shuttleworth (Eo) and Penman-Monteith crop reference evapotranspiration (crop ETo). There were two main climatic controls affecting variation in E: direct (air and water temperature) and indirect (wind-mediated change affecting the penetration of sunlight; precipitation inflow, impacting plant emergence). Lower seasonal mean Ep rates of 2.75 ± 0.89, 2.83 ± 0.91 and 3.06 ± 1.14 mm day-1 were observed in C, S and Ps, respectively, during the wet 2014. In the 2015 season, higher overall daily mean Ep rates for C, S and Ps were 3.76 ± 1.3, 4.19 ± 1.34 and 4.65 ± 1.52 mm day-1, respectively. A comparison of US Class A pan Ep containing macrophytes/sediments with that of a standard US Class A pan showed that pan coefficients (Kap and Kas) might allow for more accurate on-site lake E estimates. In 2014, seasonal mean Kas and Kap were 1.04 ± 0.14 and 1.09 ± 0.18, respectively. Slightly higher Ka values were observed during the warm and dry 2015 (Kas: 1.15 ± 0.22; Kap: 1.26 ± 0.23). A Ka value greater than 1 indicates that the Ep of a US Class A pan containing macrophytes and sediment is always higher than that of C. The calculated Eo overestimated measured Ep of Ps during the course of this study. During the warm-dry growing season, crop ETo was closest to Ep of Ps. Empirical coefficients can be useful for estimating E of lakes with submerged macrophytes more precisely. The accuracy of the estimate of Keszthely Bay's E improved by 9.85% when Ka was determined on site.

Strain typing of acetic acid bacteria responsible for vinegar production by the submerged elaboration method.

Science.gov (United States)

Fernández-Pérez, Rocío; Torres, Carmen; Sanz, Susana; Ruiz-Larrea, Fernanda

2010-12-01

Strain typing of 103 acetic acid bacteria isolates from vinegars elaborated by the submerged method from ciders, wines and spirit ethanol, was carried on in this study. Two different molecular methods were utilised: pulsed field gel electrophoresis (PFGE) of total DNA digests with a number of restriction enzymes, and enterobacterial repetitive intergenic consensus (ERIC) - PCR analysis. The comparative study of both methods showed that restriction fragment PFGE of SpeI digests of total DNA was a suitable method for strain typing and for determining which strains were present in vinegar fermentations. Results showed that strains of the species Gluconacetobacter europaeus were the most frequent leader strains of fermentations by the submerged method in the studied vinegars, and among them strain R1 was the predominant one. Results showed as well that mixed populations (at least two different strains) occurred in vinegars from cider and wine, whereas unique strains were found in spirit vinegars, which offered the most stressing conditions for bacterial growth. Copyright © 2010 Elsevier Ltd. All rights reserved.

Submerged Glow-Discharge Plasma: An Economical Approach to Convert Construction Scrap Metal into Nanomaterials

Directory of Open Access Journals (Sweden)

Yek Peter Nai Yuh

2018-01-01

Full Text Available Submerged glow-discharge plasma (SGDP is relatively new among the various methods available for nanomaterials synthesis (NMs techniques. This method allows great control over the production cost of nanomaterials synthesis. A lab-scale batch type SDGP technology has been constructed to produce nanomaterials and investigate the inter-relationship between plasma excitation voltages, electrodes submerged areas and electrolyte concentration. Metal oxide nanospheres has been synthesised from different electrolyte concentrations (1M-0.001M and characterized by Scanning Electron Microscopy (SEM and Energy Dispersive Spectroscopy (EDS. As the major results showed that the nanospheres are uniformly spherical with diameter size distribution are between 100 nm - 2μm. EDS analysis shown the nano-Iron Oxide have been formed. Scrap metal initially showed around 6.45% and 93.55% of Carbon and Iron composition respectively. After SGDP process to the scrap metal, Carbon content has increased to 34-35% and Iron content has reduced to around 15-40%. EDS results also shown the higher percentage of Iron amount has remained with lower electrolyte concentration and Current is proportionally related to submersion area of cathode.

Apparatus for the in situ inspection of tubes while submerged in a liquid

International Nuclear Information System (INIS)

Abell, G.E.; Plavsity, L.; Sattler, F.J.

1979-01-01

Apparatus is described for the in situ inspection of tubes which are submerged in a liquid such as the primary coolant of a nuclear reactor. A sensor is withdrawn from a tube by a cable. Means are provided for removing the liquid from and drying the cable. The liquid is returned to the tubes preventing the spread of deleterious liquids to otherwise benign environments and fouling of the drive mechanism used to control cable movements

Ethylene is not involved in adaptive responses to flooding in the Amazonian wild rice species Oryza grandiglumis.

Science.gov (United States)

Okishio, Takuma; Sasayama, Daisuke; Hirano, Tatsuya; Akimoto, Masahiro; Itoh, Kazuyuki; Azuma, Tetsushi

2015-02-01

The Amazonian wild rice Oryza grandiglumis has two contrasting adaptation mechanisms to flooding submergence: a quiescence response to complete submergence at the seedling stage and an escape response based on internodal elongation to partial submergence at the mature stage. We investigated possible factors that trigger these responses. In stem segments excised from mature O. grandiglumis plants, complete submergence only slightly promoted internodal elongation with increased ethylene levels in the internodes, while partial submergence substantially promoted internodal elongation without increased ethylene levels in the internodes. Incubation of non-submerged stem segments under a continuous flow of humidified ethylene-free air promoted internodal elongation to the same extent as that observed for partially submerged segments. Applied ethylene had little effect on the internodal elongation of non-submerged segments irrespective of humidity conditions. These results indicate that the enhanced internodal elongation of submerged O. grandiglumis plants is not triggered by ethylene accumulated during submergence but by the moist surroundings provided by submergence. The growth of shoots in O. grandiglumis seedlings was not promoted by ethylene or complete submergence, as is the case in O. sativa cultivars possessing the submergence-tolerant gene SUB1A. However, because the genome of O. grandiglumis lacks the SUB1A gene, the quiescence response of O. grandiglumis seedlings to complete submergence may be regulated by a mechanism distinct from that involved in the response of submergence-tolerant O. sativa cultivars. Copyright © 2014 Elsevier GmbH. All rights reserved.

Ethylene regulates fast apoplastic acidification and expansin A transcription during submergence-induced petiole elongation in Rumex palustris

NARCIS (Netherlands)

Vreeburg, RAM; Benschop, JJ; Peeters, AJM; Colmer, TD; Ammerlaan, AHM; Staal, M; Elzenga, TM; Staals, RHJ; Darley, CP; McQueen-Mason, SJ; Voesenek, LACJ

The semi-aquatic dicot Rumex palustris responds to complete submergence by enhanced elongation of young petioles. This elongation of petiole cells brings leaf blades above the water surface, thus reinstating gas exchange with the atmosphere and increasing survival in flood-prone environments. We

Properties of uracil transport by the submerged mycelium of Trichoderma viride

International Nuclear Information System (INIS)

Lakatos, B.; Betina, V.; Simkovic, M.; Varecka, L.

1998-01-01

The aim of the study is to describe the transport of uracil by the submerged mycelium of important mycoparasitic fungus Trichoderma viride. transport of radioactively labelled uracil into the submerged mycelium of Trichoderma viride was measured by means of membrane filtration technique. The high-affinity transport was temperature depend with the optimum temperature at 35 grad C. From the Arrhenius plot of the temperature dependence its activation energy could be calculated (54 kJ/mol uracil). The measurement of pH dependence showed the optimum pH at pH 6.5. High-affinity transport was inhibited with 5-fluorouracil. 5-Br-uracil, adenine, xanthine, cytosine, 5-Br-cytosine, adenosine, uridine but not with CMP, thymidine. 14 C-5-fluorouracil was taken up by T. viride mycelium in a similar way but the influx was less by about 20%. Inhibitors of RNA synthesis, rifamycin and rifampicin 9(up to 10 μg/ml) did not inhibit the uracil uptake even after 2 h preincubation wit mycelium. The results suggest that the uptake of uracil is mediated by a carrier. The uptake at sub-millimolar uracil concentrations is almost exclusively driven by the electrochemical potential of protons. The inhibitory effects of other substances presumably taken up by the mycelium may be explained by the competition for the driving force rather than for the binding site of the transporter molecule. In presence of millimolar concentrations of uracil, its osmotic gradient could itself represent the driving force for the transport. (authors)

Root Zone Respiration on Hydroponically Grown Wheat Plant Systems

Science.gov (United States)

Soler-Crespo, R. A.; Monje, O. A.

2010-01-01

Root respiration is a biological phenomenon that controls plant growth and physiological development during a plant's lifespan. This process is dependent on the availability of oxygen in the system where the plant is located. In hydroponic systems, where plants are submerged in a solution containing vital nutrients but no type of soil, the availability of oxygen arises from the dissolved oxygen concentration in the solution. This oxygen concentration is dependent on the , gas-liquid interface formed on the upper surface of the liquid, as given by Henry's Law, depending on pressure and temperature conditions. Respiration rates of the plants rise as biomass and root zone increase with age. The respiration rate of Apogee wheat plants (Triticum aestivum) was measured as a function of light intensity (catalytic for photosynthesis) and CO2 concentration to determine their effect on respiration rates. To determine their effects on respiration rate and plant growth microbial communities were introduced into the system, by Innoculum. Surfactants were introduced, simulating gray-water usage in space, as another factor to determine their effect on chemical oxygen demand of microbials and on respiration rates of the plants. It is expected to see small effects from changes in CO2 concentration or light levels, and to see root respiration decrease in an exponential manner with plant age and microbial activity.

Mutation breeding and submerged fermentation of a Pleurotus polysaccharide high-yield strain with low-energy heavy ions implantation

International Nuclear Information System (INIS)

Chen Henglei; Wan Honggui; Lv Changwu; Zeng Xianxian

2010-01-01

Pleurotus polysaccharide high-yield strains were selected through a method of auxotrophic primary screening and Shake-flask fermentation re-screening after low-energy heavy ions (the fluence of 1.2 x 10 16 N + /cm 2 at the energy of 15 keV) stepwise implantation. Two Pleurotus polysaccharide high-yield strains, PFPH-1 and PFPH-2, were selected with stable mycelium polysaccharide yield. The mycelium polysaccharide yield of PFPH-1 and PFPH-2 increased by 46.55% and 75.14%, respectively, compared to the original strain. The accumulation of mycelium biomass and intracellular polysaccharides were monitored in the submerged fermentation of Pleurotus ferulae by supplementation of various carbon and nitrogen sources as well as inorganic salts and pH alteration. The optima1 submerged fermentation medium favoring the accumulation of mycelium biomass and intracellular polysaccharides of PFPH-2 consisted of 1.0% wheat flour, 2.0% sucrose, 2.0% soybean flour, 1.5% bran extract, 0.2% K 2 HPO 4 , and 0.15% MgSO 4 ·7H 2 O, with a fittest pH value of 5.64. The orthogonal combination of the optimal carbon and nitrogen sources with inorganic salts indicates a synergistic effect on the accumulation of mycelium biomass and intracellular polysaccharides in the submerged fermentation of PFPH-2. The yield of mycelium polysaccharides of PFPH-2 increased to 903.73 ± 1.23 mg·L -1 by the end of fermentation. (authors)

Endodontic Treatment in Submerged Roots: A Case Report

Directory of Open Access Journals (Sweden)

Hemalatha Pameshwar Hiremath

2010-06-01

Full Text Available Alveolar ridge resorption has long been considered an unavoidable consequence of tooth extraction. While the extent and pattern of resorption is variable among individuals, there is a progressive loss of ridge contour as a result of physiologic bone remodeling. Even today, with best modalities of tooth preservation, there is a group of elderly individuals who do not benefit from modern preventive practices and who now present a dilemma in terms of maintaining the masticatory apparatus necessary for nutrition. Even with excellent dental care, such patients experience abrasion of the natural tooth crowns with age, and embedded roots are left within the alveolar bone. According to old concepts of dental care, extraction of these roots would have been recommended, but today’s goal of excellence in endodontics dictates otherwise. We report a case in which vital and non-vital root submergence was carried out to prevent alveolar ridge reduction.

Comparison of fouling characteristics in different pore-sized submerged ceramic membrane bioreactors.

Science.gov (United States)

Jin, Le; Ong, Say Leong; Ng, How Yong

2010-12-01

Membrane fouling, the key disadvantage that inevitably occurs continuously in the membrane bioreactor (MBR), baffles the wide-scale application of MBR. Ceramic membrane, which possesses high chemical and thermal resistance, has seldom been used in MBR to treat municipal wastewater. Four ceramic membranes with the same materials but different pore sizes, ranging from 80 to 300 nm, were studied in parallel using four lab-scale submerged MBRs (i.e., one type of ceramic membrane in one MBR). Total COD and ammonia nitrogen removal efficiencies were observed to be consistently above 94.5 and 98%, respectively, in all submerged ceramic membrane bioreactors. The experimental results showed that fouling was mainly affected by membrane's microstructure, surface roughness and pore sizes. Ceramic membrane with the roughest surface and biggest pore size (300 nm) had the highest fouling potential with respect to the TMP profile. The 80 nm membrane with a smoother surface and relatively uniform smaller pore openings experienced least membrane fouling with respect to TMP increase. The effects of the molecular weight distribution, particle size distribution and other biomass characteristics such as extracellular polymeric substances, zeta potential and capillary suction time, were also investigated in this study. Results showed that no significant differences of these attributes were observed. These observations indicate that the membrane surface properties are the dominant factors leading to different fouling potential in this study. Copyright © 2010 Elsevier Ltd. All rights reserved.

Unusual energy properties of leaky backward Lamb waves in a submerged plate.

Science.gov (United States)

Nedospasov, I A; Mozhaev, V G; Kuznetsova, I E

2017-05-01

It is found that leaky backward Lamb waves, i.e. waves with negative energy-flux velocity, propagating in a plate submerged in a liquid possess extraordinary energy properties distinguishing them from any other type of waves in isotropic media. Namely, the total time-averaged energy flux along the waveguide axis is equal to zero for these waves due to opposite directions of the longitudinal energy fluxes in the adjacent media. This property gives rise to the fundamental question of how to define and calculate correctly the energy velocity in such an unusual case. The procedure of calculation based on incomplete integration of the energy flux density over the plate thickness alone is applied. The derivative of the angular frequency with respect to the wave vector, usually referred to as the group velocity, happens to be close to the energy velocity defined by this mean in that part of the frequency range where the backward mode exists in the free plate. The existence region of the backward mode is formally increased for the submerged plate in comparison to the free plate as a result of the liquid-induced hybridization of propagating and nonpropagating (evanescent) Lamb modes. It is shown that the Rayleigh's principle (i.e. equipartition of total time-averaged kinetic and potential energies for time-harmonic acoustic fields) is violated due to the leakage of Lamb waves, in spite of considering nondissipative media. Copyright © 2017 Elsevier B.V. All rights reserved.

Navigating environmental, economic, and technological trade-offs in the design and operation of submerged anaerobic membrane bioreactors (AnMBRs)

KAUST Repository

Pretel, R.; Shoener, B.D.; Ferrer, J.; Guest, J.S.

2015-01-01

of submerged AnMBRs influence the technological, environmental, and economic sustainability of the system across its life cycle. Specific design and operational decisions evaluated included: solids retention time (SRT), mixed liquor suspended solids (MLSS

Welding of Nb micro-alloyed steel by the submerged arc process using Brazilian consumables

International Nuclear Information System (INIS)

Scotti, A.; Quites, A.M.

1982-01-01

A set of procedures was established for welding of Nb micro-alloyed steel by the submerged arc process, using national consumables, in order to simultaneously achieve a more economic welding and better mechanical properties. From all the wire-flux combinations the better were the correspondent to AWS F84ED1, F74EM12K and F84EH14, the last being the best. (Author) [pt

The influence of plant-associated filter feeders on phytoplankton biomass: a mesocosm study

NARCIS (Netherlands)

Vanderstukken, M.; Declerck, S.A.J.; Pals, A.; De Meester, L.; Muylaert, K.

2010-01-01

Low phytoplankton biomass usually occurs in the presence of submerged macrophytes, possibly because submerged macrophytes enhance top-down control of phytoplankton by offering a refuge for efficient grazers like Daphnia against fish predation. However, other field studies also suggest that submerged

The influence of permanently submerged macrophytes on sediment mercury distribution, mobility and methylation potential in a brackish Norwegian fjord.

Science.gov (United States)

Olsen, Marianne; Schaanning, Morten Thorne; Braaten, Hans Fredrik Veiteberg; Eek, Espen; Moy, Frithjof E; Lydersen, Espen

2018-01-01

Macrophytes are shown to affect the microbial activity in different aqueous environments, with an altering of the sediment cycling of mercury (Hg) as a potential effect. Here, we investigated how a meadow with permanently submerged macrophytes in a contaminated brackish fjord in southern Norway influenced the conditions for sulfate reducing microbial activity, the methyl-Hg (MeHg) production and the availability of MeHg. Historically discharged Hg from a chlor-alkali plant (60-80tons, 1947-1987) was evident through high Hg concentrations (491mgTot-Hgkg -1 , 268μgMeHgkg -1 ) in intermediate sediment depths (10-20cm) outside of the meadow, with reduced concentrations within the meadow. Natural recovery of the fjord was revealed by lower sediment surface concentrations (1.9-15.5mgTot-Hgkg -1 , 1.3-3.2μgMeHgkg -1 ). Within the meadow, vertical gradients of sediment hydrogen sulfide (H 2 S) E h and pH suggested microbial sulfate reduction in 2-5cm depths, coinciding with peak values of relative MeHg levels (0.5% MeHg). We assume that MeHg production rates was stimulated by the supply and availability of organic carbon, microbial activity and a sulfide oxidizing agent (e.g. O 2 ) within the rhizosphere. Following this, % MeHg in sediment (0-5cm) within the meadow was approximately 10× higher compared to outside the meadow. Further, enhanced availability of MeHg within the meadow was demonstrated by significantly higher fluxes (p<0.01) from sediment to overlying water (0.1-0.6ngm -2 d -1 ) compared to sediment without macrophytes (0.02-0.2ngm -2 d -1 ). Considering the productivity and species richness typical for such habitats, submerged macrophyte meadows located within legacy Hg contaminated sediment sites may constitute important entry points for MeHg into food webs. Copyright © 2017 Elsevier B.V. All rights reserved.

Observation of thermal plumes from submerged discharges in the Great Lakes and their implications for modeling and monitoring

International Nuclear Information System (INIS)

Ditmars, J.D.; Paddock, R.A.; Frigo, A.A.

1977-01-01

Measurements of thermal plumes from submerged discharges of power plant cooling waters into the Great Lakes provide the opportunity to view the mixing processes at prototype scales and to observe the effects of the ambient environment on those processes. Examples of thermal plume behavior in Great Lakes' ambient environments are presented to demonstrate the importance of measurements of the detailed structure of the ambient environment, as well as of the plumes, for interpretation of prototype data for modeling and monitoring purposes. The examples are drawn from studies by Argonne National Laboratory (ANL) at the Zion Nuclear PowerStation and the D. C. Cook Nuclear Plant on Lake Michigan and at the J. A. FitzPatrick Nuclear Power Plant on Lake Ontario. These studies included measurements of water temperatures from a moving boat which provide a quasi-synoptic view of the three-dimensional temperature structure of the thermal plume and ambient water environment. Additional measurements of water velocities, which are made with continuously recording, moored, and profiling current meters, and of wind provide data on the detailed structure of the ambient environment. The detailed structure of the ambient environment, in terms of current, current shear, variable winds, and temperature stratification, often influence greatly thermal plume behavior. Although predictive model techniques and monitoring objectives often ignore the detailed aspects of the ambient environment, useful interpretation of prototype data for model evaluation or calibration and monitoring purposes requires detailed measurement of the ambient environment. Examination of prototype thermal plume data indicates that, in several instances, attention to only the gross characteristics of the ambient environment can be misleading and could result in significant errors in model calibration and extrapolation of data bases gathered in monitoring observations

Accumulation of americium-241 in the biomass of aquatic plants of the Yenisei river: experimental study

Energy Technology Data Exchange (ETDEWEB)

Zotina, T.A.; Bolsunovsky, A.Y.A.; Bondareva, L.G. [Institute of Biophysics SB RAS, Akademgorodok, Krasnoyarsk (Russian Federation)

2004-07-01

Due to the operation of the Mining-and-Chemical Combine (Krasnoyarsk-26), which has been manufacturing weapons-grade plutonium for several decades, the Yenisei River is contaminated with transuranic elements (including {sup 241}Am). {sup 241}Am was found in the riverside soil, sediment and in the biomass of aquatic plants (Bolsunovsky et al., 1999, 2002). Aquatic plants are an important link in the migration of radionuclides in an aquatic ecosystem. In laboratory experiments, we investigated accumulation of {sup 241}Am by the submerged macrophyte from the Yenisei River: the pond weed (Elodea canadensis) and the aquatic moss (Fontinalis antipyretica), and release of {sup 241}Am from the biomass. The content of {sup 241}Am was measured on a Canberra (USA) gamma-spectrometer. The experiments showed that specific accumulation and concentration factors of {sup 241}Am in the plants were in inverse proportion to their biomass. We obtained new data on release of {sup 241}Am from the biomass of macrophyte. Americium-241 was more firmly fixed in the biomass of the aquatic moss. In 12 months, the biomass of the aquatic moss released about 30% of the initial americium activity into the water. To compare, the biomass of the pond weed released into the water medium up to 64% of the initial {sup 241}Am activity in 1.5 4 months. The release rate was dependent on the decomposition rate of the plant biomass. The experiments showed that submerged macrophyte of the Yenisei River can accumulate considerable activities of {sup 241}Am and retain americium for long periods of time in biomass. (author)

Performance of Submerged Aerated Biofilters for Wastewater Treatment and Excess Biological Sludge Production

Directory of Open Access Journals (Sweden)

Mohammad A. Baghapour

2007-01-01

Full Text Available Minimizing sludge production in the treatment facility is a reasonable measure to reduce waste in sewage treatment, especially as regards excess biological sludge. In this regard, submerged aerated filters' (SAFs have recently found increasing applications in treatment facilities. Thanks to their treatment mechanism, they have greatly contributed to reduction of waste production and, thereby, to reduced treatment costs. Biomass growths of both attached and suspended types take place in these filters. However, little attention has been paid to suspended sludge production and to its relationship with the physical properties of the filter. The design and application criterion for these filters is the organic loadings on unit of area or unit of volume of the media used in these filters. In this study, four filters with different physical properties and different specific areas were loaded with synthetic wastewater made of low-fat dry milk powder for five different hydraulic retention times to evaluate excess sludge production rates in submerged aerated filters. It was shown that increasing specific area increased SCOD removal efficiency up to a maximum level in saturated growths after which point the removal efficiency remained unchanging or decreased. The results also revealed that decreased hydraulic retention times increased sludge production rates in all the study columns and that media with higher porosity levels produced less excess sludge despite lower pollutant removal efficiency.

Nuclear power plant in the Oslofjord district

International Nuclear Information System (INIS)

Moshagen, H.; Kjeldsen, P.; Tesaker, E.

1972-01-01

Calculations of the spreading of cooling water effluent from a nuclear power plant in the waters adjacent to prospective sites in the Oslofjord district are made on the basis of the available hydrological data. Such data has been primarily that presented in reports 1-4 in the report series 'Nuclear power plant in the Oslofjord district'. In addition data from the Laboratory's previous investigations at Slagentangen and meteorological data from Norsk Institutt for Luftforskning for release points Brenntangen, Son, Langangsfjorden, Ormefjorden, Vardeaasen and Slagentangen have been used. The calculations are concentrated on trapping in layers, current effects on horizontal spreading and heat transfer through the surface. The results are presented partly as tables showing to what extent the cooling water breaks through to the surface with deeply submerged discharge and use of a diffuser, partly as diagrams showing layer zones and salinity, and partly as temperature rise curves drawn on maps of the various recipient areas. (JIW)

Continental-scale patterns of nutrient and fish effects on shallow lakes: introduction to a pan-European mesocosm experiment

NARCIS (Netherlands)

Stephen, D.; Balayla, D.; Bécares, E.; Collings, S.E.; Fernández-Aláez, C.; Fernández-Aláez, M.; Ferriol, C.; García, P.; Gomá, J.; Gyllström, M.; Hansson, L-A.; Hietala, J.; Kairesalo, T.; Rosa Miracle, M.; Romo, S.; Rueda, J.; Ståhl-Delbanco, A.; Svensson, M.; Vakkilainen, K.; Valentín, M.; van de Bund, W.; Van Donk, E.; Vicente, E.; Villena, M.J.; Moss, B.

2004-01-01

1. Shallow lake ecosystems are normally dominated by submerged and emergent plants. Biological stabilising mechanisms help preserve this dominance. The systems may switch to dominance by phytoplankton, however, with loss of submerged plants. This process usually takes place against a background of

Aquatic Plant Control Research Program. Moneoecious hydrilla in the Potomac River.

Science.gov (United States)

1985-08-01

K. Van USDA/ARS 3205 SW College Avenue Ft. Lauderdale, FL 33314 Dr. Howard E. Westerdahl * US Army Engineer Waterways Experiment Station ATTN: WESES-A...PO Box 631 Vicksburg, MS 39180-0631 * Dr. Westerdahl was primarily responsible for the development of this chapter and should be used as a point of...composition of the water system ( Westerdahl 1981). The literature is often contradictory in regard to these effects. Walker (1963) found increases in the

The use of alpha-methyl-D-glucoside, a synthetic analogue of maltose, as inducer of amylase by Aspergillus sp in solid-state and submerged fermentations

OpenAIRE

Moreira, Fabiana G.; Lenartovicz, Veridiana; Souza, Cristina G.M. de; Ramos, Edivan P.; Peralta, Rosane M.

2001-01-01

The use of a methyl-D-glucoside (alphaMG), a synthetic analogue of maltose, as carbon source and inducer of amylase synthesis to several species of Aspergillus was studied in submerged and solid-state fermentations. Among a group of ten species, A. tamarii, A. fumigatus and A. flavus were able to produce biomass and high specific amylolytic activity in submerged cultures containing alphaMG as the only carbon source. In solid state fermentation, the enrichment of basal wheat bran or corn cob m...

Start-up period investigation of pilot-scale submerged membrane electro-bioreactor (SMEBR) treating raw municipal wastewater.

Science.gov (United States)

Hasan, Shadi W; Elektorowicz, Maria; Oleszkiewicz, Jan A

2014-02-01

Submerged membrane electro-bioreactor (SMEBR) is a new hybrid technology for wastewater treatment employing electrical field and microfiltration in a nutrient-removing activated sludge process. A pilot SMEBR system was located at the wastewater treatment plant in the City of l'Assomption (Quebec, Canada) with the objective of investigating the start-up period performance under variable organic loadings and environmental conditions with respect to effluent quality, membrane fouling, and sludge properties. The pilot SMEBR facility was fed with the raw de-gritted municipal wastewater. At steady state operation, the removal efficiencies of ammonia (as NH3(+)-N), phosphorus (as PO4(3-)-P), and COD were 99%, 99%, and 92%, respectively. No substantial increase in the monitored transmembrane pressure as 0.02kPad(-1) was reported. The time necessary to filter 100mL of the sludge sample has decreased by 78% after treatment whilst the sludge volume index averaged 119mLg(-1). Energy requirements were in the range of 1.1-1.6kWhm(-3) of wastewater. It was concluded that the SMEBR is a very competitive technology when compared to conventional membrane systems as it can enhance treatment performance to an appreciable extent, remove phosphorus and reduce fouling. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Characteristics and limitations of GPS L1 observations from submerged antennas - Theoretical investigation in snow, ice, and freshwater and practical observations within a freshwater layer

Science.gov (United States)

Steiner, Ladina; Meindl, Michael; Geiger, Alain

2018-05-01

Observations from a submerged GNSS antenna underneath a snowpack need to be analyzed to investigate its potential for snowpack characterization. The magnitude of the main interaction processes involved in the GPS L1 signal propagation through different layers of snow, ice, or freshwater is examined theoretically in the present paper. For this purpose, the GPS signal penetration depth, attenuation, reflection, refraction as well as the excess path length are theoretically investigated. Liquid water exerts the largest influence on GPS signal propagation through a snowpack. An experiment is thus set up with a submerged geodetic GPS antenna to investigate the influence of liquid water on the GPS observations. The experimental results correspond well with theory and show that the GPS signal penetrates the liquid water up to three centimeters. The error in the height component due to the signal propagation delay in water can be corrected with a newly derived model. The water level above the submerged antenna could also be estimated.

Submerged cutting of steel by abrasive water jets

International Nuclear Information System (INIS)

Haferkamp, H.; Louis, H.; Meier, G.

1990-01-01

A special cutting head for underwater use was designed and built. Tests were carried out to find out useful parameters for submerged cutting. With regard to the production of secondary waste the abrasive flow rate had to be minimized. This was achieved by using a small water jet nozzle (up to 0.4 mm diameter) and a high pressure (up to 4000 bar) with an optimal abrasive flow rate of about 5 g/s. In the case of a higher ambient pressure a decrease of the cutting performance was measured. But this decrease is not important regarding decommissioning because the ambient pressure is less than 2 bar. An air mantle nozzle was adapted to the cutting head to improve the working distance under water. The air mantle surrounding the abrasive jet lowers the friction between jet and surrounding water and increases the cutting efficiency in the case of greater working distances. (author)

Submerged macrophytes shape the abundance and diversity of bacterial denitrifiers in bacterioplankton and epiphyton in the Shallow Fresh Lake Taihu, China.

Science.gov (United States)

Fan, Zhou; Han, Rui-Ming; Ma, Jie; Wang, Guo-Xiang

2016-07-01

nirK and nirS genes are important functional genes involved in the denitrification pathway. Recent studies about these two denitrifying genes are focusing on sediment and wastewater microbe. In this study, we conducted a comparative analysis of the abundance and diversity of denitrifiers in the epiphyton of submerged macrophytes Potamogeton malaianus and Ceratophyllum demersum as well as in bacterioplankton in the shallow fresh lake Taihu, China. Results showed that nirK and nirS genes had significant different niches in epiphyton and bacterioplankton. Bacterioplankton showed greater abundance of nirK gene in terms of copy numbers and lower abundance of nirS gene. Significant difference in the abundance of nirK and nirS genes also existed between the epiphyton from different submerged macrophytes. Similar community diversity yet different community abundance was observed between epiphytic bacteria and bacterioplankton. No apparent seasonal variation was found either in epiphytic bacteria or bacterioplankton; however, environmental parameters seemed to have direct relevancy with nirK and nirS genes. Our study suggested that submerged macrophytes have greater influence than seasonal parameters in shaping the presence and abundance of bacterial denitrifiers. Further investigation needs to focus on the potential contact and relative contribution between denitrifiers and environmental factors.

O-2 dynamics in the rhizosphere of young rice plants (Oryza sativa L.) as studied by planar optodes

DEFF Research Database (Denmark)

Larsen, Morten; Santner, Jakob; Oburger, Eva

2015-01-01

dynamics in the rice rhizosphere. Applying high-resolution planar optode imaging, we investigated the O-2 dynamics of plants grown in water saturated soil, as a function of ambient O-2 level, irradiance and plant development, for submerged and emerged plants. O-2 leakage was heterogeneously distributed...... with zones of intense leakage around roots tips and young developing roots. While the majority of roots exhibited high ROL others remained surrounded by anoxic soil. ROL was affected by ambient O-2 levels around the plant, as well as irradiance, indicating a direct influence of photosynthetic activity on ROL...... of the rhizosphere. The work documents that spatio-temporal measurements are important to fully understand and account for the highly variable O-2 dynamics and associated biogeochemical processes and pathways in the rice rhizosphere....

Herbivory and growth in terrestrial and aquatic populations of amphibious stream plants

DEFF Research Database (Denmark)

Sand-Jensen, Kaj; Jacobsen, Dean

2002-01-01

1. Many amphibious plant species grow in the transition between terrestrial and submerged vegetation in small lowland streams. We determined biomass development, leaf turnover rate and invertebrate herbivory during summer in terrestrial and aquatic populations of three amphibious species...... production (average 1.2-5.1%) than aquatic populations (2.9-17.3%), while the same plant dry mass was consumed per unit ground area. 3. Grazing loss increased linearly with leaf age apart from the youngest leaf stages. Grazing loss during the lifetime of leaves was therefore 2.4-3.1 times higher than mean...... apparent loss to standing leaves of all ages. The results imply that variation in density of grazers relative to plant production can account for differences in grazing impact between terrestrial and aquatic populations, and that fast leaf turnover keeps apparent grazing damage down. 4. We conclude...

Production of hydrolytic enzymes by the plant pathogenic fungus Myrothecium verrucaria in submerged cultures Produção de enzimas hidrolíticas pelo fungo fitopatogênico Myrothecium verrucaria em culturas submersas

Directory of Open Access Journals (Sweden)

Fabiana Guillen Moreira

2005-03-01

Full Text Available The capability of the plant pathogenic fungus Myrothecium verrucaria to produce extracellular hydrolytic enzymes in submerged cultures was studied using several substrates. The fungus was able to produce different depolymerases and glycosidases, being xylanase, pectinase and protease the most important. Lipase was found in cultures developed in the presence of olive oil, while protease activity was detected in all cultures. Xylanase and pectinase were optimally active at pH 4.5-5.5, while protease was active in a large range of pH 3.5 to 11.0. All three enzymes were maximally active at 40ºC and they were stable for several hours at temperature up to 50ºC.A capacidade do fungo fitopatogênico Myrothecium verrucaria produzir enzimas hidrolíticas extracelulares em culturas submersas foi estudada utilizando diversos substratos. O fungo foi capaz de produzir diferentes depolimerases e glicosidases, sendo xilanases, pectinases e proteases as mais importantes. Atividade lipase foi encontrada nos filtrados das culturas desenvolvidas na presença de óleo de oliva, enquanto atividade proteolítica foi detectada em todas as culturas. Xilanase e pectinase foram otimamente ativas em pH 4,5 a 5,5, enquanto protease foi ativa em ampla faixa de pH (3,5 a 11,0. As três enzimas foram otimamente ativas 40ºC e estáveis por várias horas a temperaturas até 50ºC.

[Effects of two submerged macrophytes on dissolved inorganic nitrogen in overlying water and interstitial water].

Science.gov (United States)

Yang, Wen-Bin; Li, Yang; Sun, Gong-Xian

2014-06-01

Ceratophyllum demersum (C. demersum) and Vallisneria spiralis L. (V. spiralis L.) were studied as model submerged macrophytes. The effects of the submerged macrophytes on the forms and concentration of the dissolved inorganic nitrogen (DIN) in the overlying water and the interstitial water, as well as the diffusion flux of DIN in the water-sediment interface were investigated by batch simulation experiment. The results indicated that the removal effect of DIN in the overlying water was better than that in the interstitial water by submerged macrophytes. The removal efficiency of DIN in the overlying water and the interstitial water followed the order of NO2(-) -N > NH4(+) -N > NO3(-) -N. The removal rate of DIN by C. demersum was higher than that of V. spiralis L. in the overlying water, while the result was converse in the interstitial water. C. demersum and V. spiralis L. decreased the diffusion flux of NH4(+) -N and NO2(-) -N, and increased the diffusion flux of NO3(-) -N significantly. Consequently, NO3(-) -N replaced NH4(+) -N and became the main form of DIN, which diffused from the interstitial water to the overlying water. The impact of the diffusion flux of NO3(-) -N between C. demersum and V. spiralis L. showed no significant difference, and the result was the same for NH4(+) -N. C. demersum and V. spiralis L. increased the width of variation of the three nitrogen forms to total DIN in the overlying water and the interstitial water, the influence on the ratio of DIN by C. demersum was greater than that of V. spiralis L. in the overlying water, while the result was opposite in the interstitial water. In general, C. demersum had more influence in the overlying water, while V. spiralis L. had more influence in the interstitial water, and the influence of DIN diffusion flux was not significant.

Conceptual design study and evaluation of an advanced treatment process applying a submerged combustion technique for spent solvents

International Nuclear Information System (INIS)

Uchiyama, Gunzo; Maeda, Mitsuru; Fijine, Sachio; Chida, Mitsuhisa; Kirishima, Kenji.

1993-10-01

An advanced treatment process based on a submerged combustion technique was proposed for spent solvents and the distillation residues containing transuranium (TRU) nuclides. A conceptual design study and the preliminary cost estimation of the treatment facility applying the process were conducted. Based on the results of the study, the process evaluation on the technical features, such as safety, volume reduction of TRU waste and economics was carried out. The key requirements for practical use were also summarized. It was shown that the process had the features as follows: the simplified treatment and solidification steps will not generate secondary aqueous wastes, the volume of TRU solid waste will be reduced less than one tenth of that of a reference technique (pyrolysis process), and the facility construction cost is less than 1 % of the total construction cost of a future large scale reprocessing plant. As for the low level wastes of calcium phosphate, it was shown that the further removal of β · γ nuclides with TRU nuclides from the wastes would be required for the safety in interim storage and transportation and for the load of shielding. (author)

Ammonia stress on nitrogen metabolism in tolerant aquatic plant-Myriophyllum aquaticum.

Science.gov (United States)

Zhou, Qingyang; Gao, Jingqing; Zhang, Ruimin; Zhang, Ruiqin

2017-09-01

Ammonia has been a major reason of macrophyte decline in the water environment, and ammonium ion toxicity should be seen as universal, even in species frequently labeled as "NH 4 + specialists". To study the effects of high NH 4 + -N stress of ammonium ion nitrogen on tolerant submerged macrophytes and investigate the pathways of nitrogen assimilation in different organisms, Myriophyllum aquaticum was selected and treated with various concentrations of ammonium ions at different times. Increasing of ammonium concentration leads to an overall increase in incipient ammonia content in leaves and stems of plants. In middle and later stages, high concentrations of NH 4 + ion nitrogen taken up by M. aquaticum decreased, whereas the content of NO 3 - ion nitrogen increased. Moreover, in M. aquaticum, the activities of the enzymes nitrate reductase, glutamine synthetase and asparagine synthetase changed remarkably in the process of alleviating NH 4 + toxicity and deficiency. The results of the present study may support the studies on detoxification of high ammonium ion content in NH 4 + -tolerant submerged macrophytes and exploration of tissue-specific expression systems. Copyright © 2017. Published by Elsevier Inc.

Accurate Determination of the Frequency Response Function of Submerged and Confined Structures by Using PZT-Patches†

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Alexandre Presas

2017-03-01

Full Text Available To accurately determine the dynamic response of a structure is of relevant interest in many engineering applications. Particularly, it is of paramount importance to determine the Frequency Response Function (FRF for structures subjected to dynamic loads in order to avoid resonance and fatigue problems that can drastically reduce their useful life. One challenging case is the experimental determination of the FRF of submerged and confined structures, such as hydraulic turbines, which are greatly affected by dynamic problems as reported in many cases in the past. The utilization of classical and calibrated exciters such as instrumented hammers or shakers to determine the FRF in such structures can be very complex due to the confinement of the structure and because their use can disturb the boundary conditions affecting the experimental results. For such cases, Piezoelectric Patches (PZTs, which are very light, thin and small, could be a very good option. Nevertheless, the main drawback of these exciters is that the calibration as dynamic force transducers (relationship voltage/force has not been successfully obtained in the past. Therefore, in this paper, a method to accurately determine the FRF of submerged and confined structures by using PZTs is developed and validated. The method consists of experimentally determining some characteristic parameters that define the FRF, with an uncalibrated PZT exciting the structure. These parameters, which have been experimentally determined, are then introduced in a validated numerical model of the tested structure. In this way, the FRF of the structure can be estimated with good accuracy. With respect to previous studies, where only the natural frequencies and mode shapes were considered, this paper discuss and experimentally proves the best excitation characteristic to obtain also the damping ratios and proposes a procedure to fully determine the FRF. The method proposed here has been validated for the

Accurate Determination of the Frequency Response Function of Submerged and Confined Structures by Using PZT-Patches†.

Science.gov (United States)

Presas, Alexandre; Valentin, David; Egusquiza, Eduard; Valero, Carme; Egusquiza, Mònica; Bossio, Matias

2017-03-22

To accurately determine the dynamic response of a structure is of relevant interest in many engineering applications. Particularly, it is of paramount importance to determine the Frequency Response Function (FRF) for structures subjected to dynamic loads in order to avoid resonance and fatigue problems that can drastically reduce their useful life. One challenging case is the experimental determination of the FRF of submerged and confined structures, such as hydraulic turbines, which are greatly affected by dynamic problems as reported in many cases in the past. The utilization of classical and calibrated exciters such as instrumented hammers or shakers to determine the FRF in such structures can be very complex due to the confinement of the structure and because their use can disturb the boundary conditions affecting the experimental results. For such cases, Piezoelectric Patches (PZTs), which are very light, thin and small, could be a very good option. Nevertheless, the main drawback of these exciters is that the calibration as dynamic force transducers (relationship voltage/force) has not been successfully obtained in the past. Therefore, in this paper, a method to accurately determine the FRF of submerged and confined structures by using PZTs is developed and validated. The method consists of experimentally determining some characteristic parameters that define the FRF, with an uncalibrated PZT exciting the structure. These parameters, which have been experimentally determined, are then introduced in a validated numerical model of the tested structure. In this way, the FRF of the structure can be estimated with good accuracy. With respect to previous studies, where only the natural frequencies and mode shapes were considered, this paper discuss and experimentally proves the best excitation characteristic to obtain also the damping ratios and proposes a procedure to fully determine the FRF. The method proposed here has been validated for the structure vibrating

AIRBORNE LASER BATHYMETRY FOR DOCUMENTATION OF SUBMERGED ARCHAEOLOGICAL SITES IN SHALLOW WATER

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M. Doneus

2015-04-01

Full Text Available Knowledge of underwater topography is essential to the understanding of the organisation and distribution of archaeological sites along and in water bodies. Special attention has to be paid to intertidal and inshore zones where, due to sea-level rise, coastlines have changed and many former coastal sites are now submerged in shallow water. Mapping the detailed inshore topography is therefore important to reconstruct former coastlines, identify sunken archaeological structures and locate potential former harbour sites. However, until recently archaeology has lacked suitable methods to provide the required topographical data of shallow underwater bodies. Our research shows that airborne topo-bathymetric laser scanner systems are able to measure surfaces above and below the water table over large areas in high detail using very short and narrow green laser pulses, even revealing sunken archaeological structures in shallow water. Using an airborne laser scanner operating at a wavelength in the green visible spectrum (532 nm two case study areas in different environmental settings (Kolone, Croatia, with clear sea water; Lake Keutschach, Austria, with turbid water were scanned. In both cases, a digital model of the underwater topography with a planimetric resolution of a few decimeters was measured. While in the clear waters of Kolone penetration depth was up to 11 meters, turbid Lake Keutschach allowed only to document the upper 1.6 meters of its underwater topography. Our results demonstrate the potential of this technique to map submerged archaeological structures over large areas in high detail providing the possibility for systematic, large scale archaeological investigation of this environment.

Plant resources in seven Jeonju City reservoirs: Osongjae, Gisijae, Sunggokjae, Gujujae, Seounjae, Hwanghakjae and Hacksojae

Directory of Open Access Journals (Sweden)

Dong-Ok Lim

2014-09-01

Full Text Available The vascular plants of the seven reservoirs of Jeonju City were identified as consisting of 309 taxa; 87 families, 231 genera, 270 species, 35 varieties, and four forms. Eight taxa of endemic Korean plants were identified, including Taxus cuspidata var. caepitosa and Aster koraiensis. Ten taxa of rare and endangered species were identified, including T. cuspidata and Penthorum chinense. A total of 26 taxa of floristic special plants were recorded: class V species (5 taxa included Magnolia kobus and Prunus yedoensis; class IV species (3 taxa included Prunus davidiana and Campanula takesimana; class III species (5 taxa included Acer palmatum and Alisma orientale. The hydrophytes of the seven reservoirs of Jeonju City were investigated and, of a total of 56 taxa, 46 taxa of emerged plants, two taxa of submerged plants, five taxa of floating-leaved plants, and three taxa of floating plants were identified. Thirty-two taxa of naturalized plants were identified. Among these, Sicyos angulatus, Lactuca scariola, Paspalum distichum var. indutum and P. distichum were identified, which are all wild plants that may disturb the ecosystem. The study suggests that these areas require management for the physical removal of these wild plants.

US Department of Agriculture/Corps of Engineers Cooperative Aquatic Plant Control Research. Annual Report for FY 1982. Biological and Chemical Control Technologies.

Science.gov (United States)

1984-08-01

pollen. Fruits and seeds have not yet been observed in the United States. Pollination . Although the female hydrilla flower has been abundant at many U.S...The flowers can only be pollinated in the air. The female flower reaches the water surface by elongation of the hypanthium (flower "stalk"). The petals...Both the experimental herbicides N-252 and S-734 were effective against waterhyacinth at the treatment rate of 5.6 kg/ha (Table 30). Water lettuce was

Existence of equilibrium states of hollow elastic cylinders submerged in a fluid

Directory of Open Access Journals (Sweden)

M. B. M. Elgindi

1992-01-01

Full Text Available This paper is concerned with the existence of equilibrium states of thin-walled elastic, cylindrical shell fully or partially submerged in a fluid. This problem obviously serves as a model for many problems with engineering importance. Previous studies on the deformation of the shell have assumed that the pressure due to the fluid is uniform. This paper takes into consideration the non-uniformity of the pressure by taking into account the effect of gravity. The presence of a pressure gradient brings additional parameters to the problem which in turn lead to the consideration of several boundary value problems.

Statistical Optimization of Tannase Production by Penicillium sp. EZ-ZH390 in Submerged Fermentation

OpenAIRE

Zohreh Hamidi-Esfahani; Mohammad Ali Sahari; Mohammad Hossein Azizi

2015-01-01

Tannase has several important applications in food, feed, chemical and pharmaceutical industries. In the present study, production of tannase by mutant strain, Penicillium sp. EZ-ZH390, was optimized in submerged fermentation utilizing two statistical approaches. At first step, a one factor at a time design was employed to screen the preferable nutriments (carbon and nitrogen sources of the medium) to produce tannase. Screening of the carbon source resulted in the production of 10.74 U/mL of ...

Microstructural changes of a thermally aged stainless steel submerged arc weld overlay cladding of nuclear reactor pressure vessels

Science.gov (United States)

Takeuchi, T.; Kameda, J.; Nagai, Y.; Toyama, T.; Matsukawa, Y.; Nishiyama, Y.; Onizawa, K.

2012-06-01

The effect of thermal aging on microstructural changes in stainless steel submerged arc weld-overlay cladding of reactor pressure vessels was investigated using atom probe tomography (APT). In as-received materials subjected to post-welding heat treatments (PWHTs), with a subsequent furnace cooling, a slight fluctuation of the Cr concentration was observed due to spinodal decomposition in the δ-ferrite phase but not in the austenitic phase. Thermal aging at 400 °C for 10,000 h caused not only an increase in the amplitude of spinodal decomposition but also the precipitation of G phases with composition ratios of Ni:Si:Mn = 16:7:6 in the δ-ferrite phase. The degree of the spinodal decomposition in the submerged arc weld sample was similar to that in the electroslag weld one reported previously. We also observed a carbide on the γ-austenite and δ-ferrite interface. There were no Cr depleted zones around the carbide.

Microstructural changes of a thermally aged stainless steel submerged arc weld overlay cladding of nuclear reactor pressure vessels

Energy Technology Data Exchange (ETDEWEB)

Takeuchi, T., E-mail: takeuchi.tomoaki@jaea.go.jp [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Kameda, J. [National Institute for Materials Science, Sengen, Tsukuba 305-0047 (Japan); Nagai, Y.; Toyama, T.; Matsukawa, Y. [Oarai Center, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Nishiyama, Y.; Onizawa, K. [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)

2012-06-15

The effect of thermal aging on microstructural changes in stainless steel submerged arc weld-overlay cladding of reactor pressure vessels was investigated using atom probe tomography (APT). In as-received materials subjected to post-welding heat treatments (PWHTs), with a subsequent furnace cooling, a slight fluctuation of the Cr concentration was observed due to spinodal decomposition in the {delta}-ferrite phase but not in the austenitic phase. Thermal aging at 400 Degree-Sign C for 10,000 h caused not only an increase in the amplitude of spinodal decomposition but also the precipitation of G phases with composition ratios of Ni:Si:Mn = 16:7:6 in the {delta}-ferrite phase. The degree of the spinodal decomposition in the submerged arc weld sample was similar to that in the electroslag weld one reported previously. We also observed a carbide on the {gamma}-austenite and {delta}-ferrite interface. There were no Cr depleted zones around the carbide.

Physiological and Biochemical Responses of Saltmarsh Plant Spartina alterniflora to Long-term Wave Exposure

Science.gov (United States)

Zhou, W.

2017-12-01

In recent years, ecosystem-based flood defence, i.e., eco-shoreline or living shoreline, that is more sustainable and cost-effective than conventional coastal engineering structures has been brought into large-scale practice. Numerous laboratory experiments have been performed to explore the wave-attenuation effects of saltmarsh plants that are widely used in eco-shoreline, and yet no study has ever been conducted on the physiological and biochemical responses of saltmarsh plants to long-term wave exposure, presumably due to the constraint that traditional wave generator fails to provide long-term stable wave conditions necessary for physiological experiments. In this study, a long-term shallow water wave environment simulator using crank-yoke mechanism was built in the laboratory to address this gap. Experiments using the wave simulator were conducted for 8 weeks in a greenhouse and the temperature was maintained at 24-30°C. 5‰ artificial sea water was filled in the test tank, and the water was changed every week. After being acclimatized, nine S. alterniflora individual plants (initial height 30 cm) were planted in each of the three streamlined cuboid containers (12cm×12cm×20cm), which were partially submerged in a test tank, and undertook horizontal sinusoidal motion imposed by the crank-yoke mechanism to mimic plants exposed to shallow water waves. The substrate filled in the containers were soils collected from the Yellow River Delta, so were the S. alterniflora plants. A realistic stem density of 400 stems/m2 was tested, which corresponded to a grid spacing of 5.0 cm. Shallow water waves with six wave heights (H: 0.041, 0.055, 0.069, 0.033, 0.044 and 0.056m), one plants submerged depth (0.1m) and two wave periods (2s and 3s) were simulated in the experiments. A no wave condition was also tested as control. Key physiological and biochemical parameters, such as stem length, peroxidase activity, catalase, superoxide dismutase, ascorbate peroxidase, etc

Emerging and Submerging Shorelines: Impacts of Physical Change on Bioband Length

Science.gov (United States)

Kruger, L. E.; Johnson, A. C.; Gregovich, D.; Buma, B.; Noel, J.

2017-12-01

We approximated shifts in coastal benthic species for shoreline length units undergoing both sea level rise and relative sea level lowering (often post-glacial, termed isostatic rebound) where subsistence-based, southeast Alaska Natives reside. From six community centers, we examined 30 km radii shoreline reaches by merging relevant portions of the NOAA ShoreZone database with near shore bathymetry and measures of mean global sea level rise with local global positioning system information (GIS) of tectonic shift and isostatic rebound. For our analysis, we estimated change for 9,868 assessed shoreline length units having uniform substrate and biologic type over a 100-yr time span (2008-2108) using geometric analysis of shoreline attributes. For each shoreline length unit we assessed relationships among substrate, slope, exposure, and presence of five benthic species including eel grass (Zostera marina), blue mussel (Mytilus edulis), butter clams (Saxidomus gigantean), bull kelp (Nereocytis leutkeana), and foliose red algae including ribbon kelp (Palmaria sp.). Our research indicates that both emergence, up to 1.8 m, and submergence, up 0.2 m, of the land will result in disportionately larger shoreline length segment alterations for habitats in protected low-slope gradient bays and estuaries (dominated by eelgrass and butter clam habitats) with less change for rocky steep-gradient exposed penninsulas (red algae and canopy kelp). This trend, holding true regardless of isostatic rebound, tectonic shift or sea level rise rate, highlights the importance of initial geomorphology-based assessments serving to improve bio-physical, chemical, and socially-related coastal research. Where shorelines are emerging 30% decreases in estuary lengths are predicted, but where shorelines are submerging up to 3% increases in estuaries are expected. Our research results are consistent with anthropology studies assessing past coastal change. Coastal change, influencing subsistance foods

Using natural and synthetic growth regulators of plants in industrial mycology and malting

Directory of Open Access Journals (Sweden)

O. V. Kuznetcova

2010-07-01

Full Text Available Data on the expansion of the use the plants growth regulators in different areas are presented. The positive impact of the growth stimulators on the development of the Pleurotus ostreatus mycelium’s on agar nutrient media during surface cultivation is shown. The results for growth regulators stimulating effect on the fungus biosynthetic activity in submerged cultures are obtained. The possibility of using fumar and heteroauxin for malting is considered. The decline of malting time and increase of amylolytic activity of the malt are recorded.

Influence of light intensity on the toxicity of atrazine to the submerged freshwater aquatic macrophyte Elodea canadensis.

Science.gov (United States)

Brain, Richard A; Hoberg, James; Hosmer, Alan J; Wall, Steven B

2012-05-01

Light intensity can have a profound influence on the degree of phytotoxicity experienced by plants exposed to photosystem II (PSII) inhibiting herbicides. This relationship was evaluated in the submerged aquatic macrophyte Elodea canadensis exposed to three different concentrations of atrazine (510, 1000 and 2000 μg a.i./L) plus an untreated control at three different light intensities (0, 500 and 6000 lx) under static-renewal conditions for 14 days. Under 500 lx light intensity, control plants demonstrated a rapid increase in shoot length but minimal increase in dry shoot weight, suggesting limited photosynthesis. Based on shoot-length and biomass, growth was not affected by any atrazine exposure relative to controls under dark conditions (0 lx). Under low-light conditions at 500 lx, exposures to 510, 1000 and 2000 μg a.i./L atrazine significantly decreased net shoot lengths by 34%, 38% and 35%, respectively, relative to corresponding (500 lx) controls. However, atrazine exposure under this light condition did not significantly decrease biomass (dry shoot weight). Compared to 6000 lx, only approximately 8% of photosynthetically active radiation (PAR) was measured under 500 lx intensity, indicating that minimal PAR was available for photosynthesis. Under optimal light conditions (6000 lx), net shoot lengths significantly decreased in the treated atrazine groups by 48%, 51% and 68%, and net dry shoot weights (biomass) were significantly decreased by 79%, 81% and 91%, respectively, relative to corresponding (6000 lx) controls. These data show that under low light conditions, atrazine-induced effects on dry shoot weight (biomass) are dependent on available PAR and active photosynthesis. Copyright © 2011 Elsevier Inc. All rights reserved.

Xylanase production by a newly isolated Aspergillus niger SS7 in submerged culture.

Science.gov (United States)

Bakri, Yasser; Al-Jazairi, Manal; Al-Kayat, Ghassan

2008-01-01

Xylanase production by a newly isolated Aspergillus niger SS7 was studied in submerged culture. The optimum initial pH for xylanase production was found to be 7.0. Different agricultural and industrial wastes were evaluated for their ability to induce xylanase production by this isolate. The best xylanase production (293.82 IU/ml) was recorded at 3% (w/v) corn cob hulls after 120 h of incubation. The Aspergillus niger SS7 isolate grown in a simple medium, proved to be a promising microorganism for xylanase production.

Submerged Aquatic Vegetation observations from Coastal Alabama, Gulf of Mexico from 2015-05-01 to 2016-06-21 (NCEI Accession 0161265)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set consists of GIS data documenting the location, species composition, and other habitat characteristics of submerged aquatic vegetation (SAV) in coastal...

Submerged Aquatic Vegetation observations from Coastal Alabama, Gulf of Mexico from 2002-07-23 to 2003-04-17 (NCEI Accession 0162519)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Mobile Bay National Estuary Program (MBNEP) contracted Barry A. Vittor and Associates, Inc. to conduct digital aerial image surveys of submerged aquatic...

Experimental investigation on fluid flow and heat transfer characteristics of a submerged combustion vaporizer

International Nuclear Information System (INIS)

Han, Chang-Liang; Ren, Jing-Jie; Wang, Yan-Qing; Dong, Wen-Ping; Bi, Ming-Shu

2017-01-01

Highlights: • Thermal performance analysis of submerged combustion vaporizer (SCV) was performed experimentally. • Visualization study of shell-side flow field for SCV was carried out. • The effects of various operational parameters on the overall system performance were discussed. • Two new non-dimensional Nusselt correlations were proposed to predict the heat transfer performance of SCV. - Abstract: Submerged combustion vaporizer (SCV) occupies a decisive position in liquefied natural gas (LNG) industrial chain. In this paper, a visual experimental apparatus was established to have a comprehensive knowledge about fluid flow and heat transfer performance of SCV. Trans-critical liquid nitrogen (LN_2) was selected as alternative fluid to substitute LNG because of safety reason. Some unique experimental phenomena inside the SCV (local water bath freezes on the external surface of tube bundle) were revealed. Meanwhile the influences of static water height, superficial flue gas velocity, heat load, tube-side inlet pressure and tube-side mass flux on the system performance were systematically discussed. Finally, based on the obtained experimental results, two new empirical Nusselt number correlations were regressed to predict the shell-side and tube-side heat transfer characteristics of SCV. The maximum errors between predicted results and experimental data were respectively ±25% and ±20%. The outcomes of this paper were critical to the optimum design and economical operation of SCV.

Development of a ROV Deployed Video Analysis Tool for Rapid Measurement of Submerged Oil/Gas Leaks

Energy Technology Data Exchange (ETDEWEB)

Savas, Omer [Univ. of California, Berkeley, CA (United States)

2017-04-03

Expanded deep sea drilling around the globe makes it necessary to have readily available tools to quickly and accurately measure discharge rates from accidental submerged oil/gas leak jets for the first responders to deploy adequate resources for containment. We have developed and tested a field deployable video analysis software package which is able to provide in the field sufficiently accurate flow rate estimates for initial responders in accidental oil discharges in submarine operations. The essence of our approach is based on tracking coherent features at the interface in the near field of immiscible turbulent jets. The software package, UCB_Plume, is ready to be used by the first responders for field implementation. We have tested the tool on submerged water and oil jets which are made visible using fluorescent dyes. We have been able to estimate the discharge rate within 20% accuracy. A high end WINDOWS laptop computer is suggested as the operating platform and a USB connected high speed, high resolution monochrome camera as the imaging device are sufficient for acquiring flow images under continuous unidirectional illumination and running the software in the field. Results are obtained over a matter of minutes.

Three-Dimensional Flow Behavior Inside the Submerged Entry Nozzle

Science.gov (United States)

Real-Ramirez, Cesar Augusto; Carvajal-Mariscal, Ignacio; Sanchez-Silva, Florencio; Cervantes-de-la-Torre, Francisco; Diaz-Montes, Jesus; Gonzalez-Trejo, Jesus

2018-05-01

According to various authors, the surface quality of steel depends on the dynamic conditions that occur within the continuous casting mold's upper region. The meniscus, found in that upper region, is where the solidification process begins. The liquid steel is distributed into the mold through a submerged entry nozzle (SEN). In this paper, the dynamic behavior inside the SEN is analyzed by means of physical experiments and numerical simulations. The particle imaging velocimetry technique was used to obtain the vector field in different planes and three-dimensional flow patterns inside the SEN volume. Moreover, large eddy simulation was performed, and the turbulence model results were used to understand the nonlinear flow pattern inside the SEN. Using scaled physical and numerical models, quasi-periodic behavior was observed due to the interaction of two three-dimensional vortices that move inside the SEN lower region located between the exit ports of the nozzle.

A new approach on anti-vortex devices at water intakes including a submerged water jet

Science.gov (United States)

Tahershamsi, Ahmad; Rahimzadeh, Hassan; Monshizadeh, Morteza; Sarkardeh, Hamed

2018-04-01

A new approach on anti-vortex methods as hydraulic-based anti-vortex was investigated experimentally in the present study. In the investigated method, a submerged water jet is used as the anti-vortex mechanism. The added jet acts as a source of external momentum. This leads to change the intake-induced hydrodynamic pattern in the near-field of the intake structure, which can prevent formation of undesirable intake vortices. The experiments were carried out on a horizontal pipe intake. By performing 570 test cases in two different categories, including the inclined jet with respect to the axis of the intake, and the inclined jet with respect to the water surface, the effects of the jet inclination angle on the anti-vortex performance were investigated. It was found that the inclined jet with respect to the water surface is the best alternative to consider as the water jet injection pattern. Results showed that using the inclined jet with respect to the water surface can simply reduce the amounts of the expected water jet momentum more than 50% compared to that of the similar condition of the horizontal injection pattern. Moreover, it was concluded that the intake critical submergence can easily be minimized using the inclined jet with respect to the water surface.

Chemical fractionation of radionuclides and stable elements in aquatic plants of the Yenisei River.

Science.gov (United States)

Bolsunovsky, Alexander

2011-09-01

The Yenisei River is contaminated with artificial radionuclides released by one of the Russian nuclear plants. The aquatic plants growing in the radioactively contaminated parts of the river contain artificial radionuclides. The aim of the study was to investigate accumulation of artificial radionuclides and stable elements by submerged plants of the Yenisei River and estimate the strength of their binding to plant biomass by using a new sequential extraction scheme. The aquatic plants sampled were: Potamogeton lucens, Fontinalis antipyretica, and Batrachium kauffmanii. Gamma-spectrometric analysis of the samples of aquatic plants has revealed more than 20 radionuclides. We also investigated the chemical fractionation of radionuclides and stable elements in the biomass and rated radionuclides and stable elements based on their distribution in biomass. The greatest number of radionuclides strongly bound to biomass cell structures was found for Potamogeton lucens and the smallest for Batrachium kauffmanii. For Fontinalis antipyretica, the number of distribution patterns that were similar for both radioactive isotopes and their stable counterparts was greater than for the other studied species. The transuranic elements (239)Np and (241)Am were found in the intracellular fraction of the biomass, and this suggested their active accumulation by the plants.

Application of Elovich equation on uptake kinetics of 137Cs by living freshwater macrophytes - a short duration laboratory study

International Nuclear Information System (INIS)

Jaison, T.J.; Patra, A.K.; Ravi, P.M.; Tripathi, R.M.

2014-01-01

Application of Elovich equation on uptake kinetics of 137 Cs by two living macrophytes during controlled experiments on short duration exposure is studied. Compliance to 2 nd order kinetics indicates the mechanism could be chemi-sorption, involving polar functional groups present on the extracelluar surface of the macrophytes. Data analysis suggests that Myriophyllum s. exhibits faster adsorption rate than Hydrilla v. As Myriophyllum s. exhibits better kinetics than Hydrilla v., former could be a better natural adsorbing media for 137 Cs. (author)

Secretome analysis of Trichoderma reesei and Aspergillus niger cultivated by submerged and sequential fermentation processes: Enzyme production for sugarcane bagasse hydrolysis.

Science.gov (United States)

Florencio, Camila; Cunha, Fernanda M; Badino, Alberto C; Farinas, Cristiane S; Ximenes, Eduardo; Ladisch, Michael R

2016-08-01

Cellulases and hemicellulases from Trichoderma reesei and Aspergillus niger have been shown to be powerful enzymes for biomass conversion to sugars, but the production costs are still relatively high for commercial application. The choice of an effective microbial cultivation process employed for enzyme production is important, since it may affect titers and the profile of protein secretion. We used proteomic analysis to characterize the secretome of T. reesei and A. niger cultivated in submerged and sequential fermentation processes. The information gained was key to understand differences in hydrolysis of steam exploded sugarcane bagasse for enzyme cocktails obtained from two different cultivation processes. The sequential process for cultivating A. niger gave xylanase and β-glucosidase activities 3- and 8-fold higher, respectively, than corresponding activities from the submerged process. A greater protein diversity of critical cellulolytic and hemicellulolytic enzymes were also observed through secretome analyses. These results helped to explain the 3-fold higher yield for hydrolysis of non-washed pretreated bagasse when combined T. reesei and A. niger enzyme extracts from sequential fermentation were used in place of enzymes obtained from submerged fermentation. An enzyme loading of 0.7 FPU cellulase activity/g glucan was surprisingly effective when compared to the 5-15 times more enzyme loadings commonly reported for other cellulose hydrolysis studies. Analyses showed that more than 80% consisted of proteins other than cellulases whose role is important to the hydrolysis of a lignocellulose substrate. Our work combined proteomic analyses and enzymology studies to show that sequential and submerged cultivation methods differently influence both titers and secretion profile of key enzymes required for the hydrolysis of sugarcane bagasse. The higher diversity of feruloyl esterases, xylanases and other auxiliary hemicellulolytic enzymes observed in the enzyme

Air–water interface of submerged superhydrophobic surfaces imaged by atomic force microscopy

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Markus Moosmann

2017-08-01

Full Text Available Underwater air retention of superhydrophobic hierarchically structured surfaces is of increasing interest for technical applications. Persistent air layers (the Salvinia effect are known from biological species, for example, the floating fern Salvinia or the backswimmer Notonecta. The use of this concept opens up new possibilities for biomimetic technical applications in the fields of drag reduction, antifouling, anticorrosion and under water sensing. Current knowledge regarding the shape of the air–water interface is insufficient, although it plays a crucial role with regards to stability in terms of diffusion and dynamic conditions. Optical methods for imaging the interface have been limited to the micrometer regime. In this work, we utilized a nondynamic and nondestructive atomic force microscopy (AFM method to image the interface of submerged superhydrophobic structures with nanometer resolution. Up to now, only the interfaces of nanobubbles (acting almost like solids have been characterized by AFM at these dimensions. In this study, we show for the first time that it is possible to image the air–water interface of submerged hierarchically structured (micro-pillars surfaces by AFM in contact mode. By scanning with zero resulting force applied, we were able to determine the shape of the interface and thereby the depth of the water penetrating into the underlying structures. This approach is complemented by a second method: the interface was scanned with different applied force loads and the height for zero force was determined by linear regression. These methods open new possibilities for the investigation of air-retaining surfaces, specifically in terms of measuring contact area and in comparing different coatings, and thus will lead to the development of new applications.

Ecogenotoxicity testing of aquatic environment by comet assay in plants

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Anita Mukherjee

2015-05-01

Full Text Available One of the goals of environmental monitoring is the detection of potentially hazardous compounds in water. We have set up a standard method to apply the Comet assay in aquatic plants that could be of great interest to evaluate cytotoxicity, genotoxicity and oxidative stress on the same species regarded as most sensitive to environmental pollutants. The aim of the present study was to set up of standardized procedure to evaluate genotoxicity in aquatic plants- Ceratophyllum demersum one that is submerged free floating and the other is Lemna minor - a fresh water floating plant by Comet assay. Electrophoresis and unwinding times were adapted to obtain minimum DNA migration evaluated as tail intensity % or tail moment in the control group and, at the same time maximum sensitivity for DNA damage with known genotoxicants. We further investigated the cytotoxicity and oxidative stress induced in the same species. Based on the repeatability of results obtained we suggest that Ceratophyllum, Lemna can serve as model species and Comet assay could be adopted to monitor the eco-genotoxicity of water pollutants.

Habitat selection of the pink shrimp Farfantepenaeus paulensis and the blue crab Callinectes sapidus in an estuary in southern Brazil: influence of salinity and submerged seagrass meadows

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Vinicius Mendes Ruas

Full Text Available This study was conducted in two estuarine inlets (Saco da Mangueira and Saco do Arraial at the Patos Lagoon estuary, southern Brazil. The changes in relative abundance and size of post-larvae and juvenile shrimp Farfantepenaeus paulensis and juvenile blue crab Callinectes sapidus were compared, considering the influence of salinity and the presence of submerged seagrass meadows. The analyses were performed using generalized linear models (GLM for abundance variations and ANOVA for variations on the size of individuals. The pink shrimp was more abundant at Saco da Mangueira, in seagrass meadows and areas of higher salinity. The blue crab was more abundant at Saco do Arraial and in lower levels of salinity. The importance of submerged vegetation for the blue crab lies in a preference of smaller crabs of the species for the seagrass meadows. It has been shown that these species choose different habitats in the estuary, and both the salinity and the presence of submerged seagrass meadows influence the selection of habitat.

ANN Model for Predicting the Impact of Submerged Aquatic Weeds Existence on the Hydraulic Performance of Branched Open Channel System Accompanied by Water Structures

International Nuclear Information System (INIS)

Abdeen, Mostafa A. M.; Abdin, Alla E.

2007-01-01

The existence of hydraulic structures in a branched open channel system urges the need for considering the gradually varied flow criterion in evaluating the different hydraulic characteristics in this type of open channel system. Computations of hydraulic characteristics such as flow rates and water surface profiles in branched open channel system with hydraulic structures require tremendous numerical effort especially when the flow cannot be assumed uniform. In addition, the existence of submerged aquatic weeds in this branched open channel system adds to the complexity of the evaluation of the different hydraulic characteristics for this system. However, this existence of aquatic weeds can not be neglected since it is very common in Egyptian open channel systems. Artificial Neural Network (ANN) has been widely utilized in the past decade in civil engineering applications for the simulation and prediction of the different physical phenomena and has proven its capabilities in the different fields. The present study aims towards introducing the use of ANN technique to model and predict the impact of submerged aquatic weeds existence on the hydraulic performance of branched open channel system. Specifically the current paper investigates a branched open channel system that consists of main channel supplies water to two branch channels that are infested by submerged aquatic weeds and have water structures such as clear over fall weirs and sluice gates. The results of this study showed that ANN technique was capable, with small computational effort and high accuracy, of predicting the impact of different infestation percentage for submerged aquatic weeds on the hydraulic performance of branched open channel system with two different hydraulic structures

Stainless steel submerged arc weld fusion line toughness

International Nuclear Information System (INIS)

Rosenfield, A.R.; Held, P.R.; Wilkowski, G.M.

1995-04-01

This effort evaluated the fracture toughness of austenitic steel submerged-arc weld (SAW) fusion lines. The incentive was to explain why cracks grow into the fusion line in many pipe tests conducted with cracks initially centered in SAWS. The concern was that the fusion line may have a lower toughness than the SAW. It was found that the fusion line, Ji. was greater than the SAW toughness but much less than the base metal. Of greater importance may be that the crack growth resistance (JD-R) of the fusion line appeared to reach a steady-state value, while the SAW had a continually increasing JD-R curve. This explains why the cracks eventually turn to the fusion line in the pipe experiments. A method of incorporating these results would be to use the weld metal J-R curve up to the fusion-line steady-state J value. These results may be more important to LBB analyses than the ASME flaw evaluation procedures, since there is more crack growth with through-wall cracks in LBB analyses than for surface cracks in pipe flaw evaluations

Fuel handling system of nuclear reactor plants

International Nuclear Information System (INIS)

Faulstich, D.L.

1991-01-01

This patent describes a fuel handing system for nuclear reactor plants comprising a reactor vessel having an openable top and removable cover for refueling and containing therein, submerged in coolant water substantially filling the reactor vessel, a fuel core including a multiplicity of fuel bundles formed of groups of sealed tube elements enclosing fissionable fuel assembled into units. It comprises a fuel bundle handing platform moveable over the open top of the reactor vessel; a fuel bundle handing mast extendable downward from the platform with a lower end projecting into the open top reactor vessel to the fuel core submerged in water; a grapple head mounted on the lower end of the mast provided with grappling hook means for attaching to and transporting fuel bundles into and out from the fuel core; and a camera with a prismatic viewing head surrounded by a radioactive resisting quartz cylinder and enclosed within the grapple head which is provided with at least three windows with at least two windows provided with an angled surface for aiming the camera prismatic viewing head in different directions and thereby viewing the fuel bundles of the fuel core from different perspectives, and having a cable connecting the camera with a viewing monitor located above the reactor vessel for observing the fuel bundles of the fuel core and for enabling aiming of the camera prismatic viewing head through the windows by an operator

Survival of Ranunculus repens L. (creeping buttercup) in an amphibious habitat.

Science.gov (United States)

Lynn, D E; Waldren, S

2003-01-01

The turlough form of Ranunculus repens is subjected to several months' complete inundation with hard groundwater. Experimental flooding to the level of the soil surface had no effect on turlough or ruderal populations relative to drained controls. Experimental submergence resulted in direct tissue death of the ruderal population but did not affect the turlough population relative to drained controls. There was no detectable difference in the proportion of aerenchyma in drained, flooded and submerged roots of plants from either population. The proportion of aerenchyma increased with root age in the ruderal population. Up to twice the proportion of aerenchyma occurred in the lower third of the root in the turlough population relative to the middle and upper thirds. Submergence in artificially hardened tap water increased the amount of tissue death in the ruderal population, whereas it appeared to enhance the growth of plants from the turlough population relative to that of plants submerged in tap water. Only the ruderal population demonstrated a depth accommodation response in submerged conditions. Root concentrations of ethanol-soluble carbohydrates were up to three times higher in a field- collected turlough population during winter and autumn months than those in a ruderal population. Low levels of ethanol-insoluble carbohydrates were present in the turlough population but were absent from the ruderal population. Starch concentrations fluctuated greatly in the turlough population and were generally higher than those in the ruderal population. These results, together with those from previous investigations, suggest that the turlough population survives prolonged submergence by maintaining low levels of submerged photosynthesis, which may circulate oxygen within the plant tissues, and by utilizing storage carbohydrates for maintenance respiration. Copyright 2003 Annals of Botany Company

Diversification of gene expression during formation of static submerged biofilms by Escherichia coli

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Olga Besharova

2016-10-01

Full Text Available Many bacteria primarily exist in nature as structured multicellular communities, so called biofilms. Biofilm formation is a highly regulated process that includes the transition from the motile planktonic to sessile biofilm lifestyle. Cellular differentiation within a biofilm is a commonly accepted concept but it remains largely unclear when, where and how exactly such differentiation arises. Here we used fluorescent transcriptional reporters to quantitatively analyze spatio-temporal expression patterns of several groups of genes during the formation of submerged Escherichia coli biofilms in an open static system. We first confirm that formation of such submerged biofilms as well as pellicles at the liquid-air interface requires the major matrix component, curli, and flagella-mediated motility. We further demonstrate that in this system, diversification of gene expression leads to emergence of at least three distinct subpopulations of E. coli, which differ in their levels of curli and flagella expression, and in the activity of the stationary phase sigma factor σS. Our study reveals mutually exclusive expression of curli fibers and flagella at the single cell level, with high curli levels being confined to dense cell aggregates/microcolonies and flagella expression showing an opposite expression pattern. Interestingly, despite the known σS-dependence of curli induction, there was only a partial correlation between the σS activity and curli expression, with subpopulations of cells having high σS activity but low curli expression and vice versa. Finally, consistent with different physiology of the observed subpopulations, we show striking differences between the growth rates of cells within and outside of aggregates.