scholarly journals 355 Effect of Season on Nitrate Accumulation in Hydroponic Lettuce

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 453D-453
Author(s):  
Martin P.N. Gent
Keyword(s):  
Nutrient Solution ◽  
Nitrate Concentration ◽  
Leaf Tissue ◽  
Solution Concentration ◽  
Mineral Elements ◽  
Essential Elements ◽  
High Concentration ◽  
Nitrate Accumulation ◽  
Nitrate Supply ◽  
N Treatment

Serial plantings of hydroponic lettuce were grown throughout the year in the northeast United States to determine how sunlight intensity and solution nitrate affect nitrate in leaf tissue. Two nutrient solutions were used. All essential elements were supplied at the same concentration, except nitric acid was added to the high-N treatment to increase nitrate to 5.7 mm (352 ppm), compared to 4.0 mm (248 ppm) in the low-N treatment. A feedback control system maintained a constant conductivity and volume in the recirculating nutrient solution. The actual nitrate concentration in solution was higher in winter than in summer. In winter, it rose to 800 ppm in the high-N solution, while it remained below 200 ppm in the low-N solution. In summer, nitrate was 200 to 400 ppm in the high-N solution, compared to 40 to 120 ppm in the low-N solution. Concentration of other mineral elements remained at levels similar to the original formulation. Nitrate concentration in leaf tissue when the lettuce plants reached a marketable size was sensitive to sunlight and nitrate supply. In spring and summer, tissue nitrate was as low as 1100 ppm. It increased to about 4000 ppm in lettuce grown in mid-winter in a shaded greenhouse and fed high-N solution, while low-N plants had less than 3000 ppm nitrate. Tissue nitrate was related to solution nitrate. Tissue nitrate increased in proportion to solution nitrate, up to about 400 ppm nitrate in solution, then leveled off at a concentration of about 4000 ppm in the leaves, a relation that was the same under all sunlight intensities. The accumulation of nitrate in the nutrient solution was one cause of the high concentration of nitrate in lettuce leaves.

scholarly journals RESPONSE OF CATHARANTHUS ROSEUS “GRAPE COOLER” TO MEDIA AND FERTILIZER SOLUTION CONCENTRATION USING SUBIRRIGATION

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 687c-687
Author(s):  
G.C. Elliott ◽  
R.J. McAvoy ◽  
M. Abbott
Keyword(s):  
Electrical Conductivity ◽  
Catharanthus Roseus ◽  
Leaf Tissue ◽  
Solution Concentration ◽  
Essential Elements ◽  
Fresh Weight ◽  
The Third ◽  
Saturated Media ◽  
Final Harvest ◽  
Fertilizer Solution

Seedlings of Catharanthus roseus “Grape Cooler” was transplanted to cell packs of media: peat-vermiculite-perlite (MM220), peat-hydrophilic rockwool (ABS), and peat-hydrophobic rockwool (REP) and grown in subirrigation trays using 20N-4.4P-17K fertilizer at 50, 150 or 250 ppm N applied at each irrigation. Shoots of four plants in each of two replications were harvested 2, 3, 4 and 5 after transplant. Leaf samples from the third harvest were analyzed for essential elements. Electrical conductivity (EC) was measured in saturated media extracts at each harvest. Significant media by fertilizer interactions were obtained for fresh weight and leaf area at the final harvest. Greatest growth was obtained with 50 ppm N in ABS, but with 150 ppm N in MM 220 and REP. In tehse, growth was similar at 50 and 150 ppm N, but less growth REP than MM220 at 250 ppm. More growth was produced with ABS at 50 ppm N, but less at 150 or 250 ppm N. Leaf tissue N increased 38.5 to 54.5 mg g-1 dry wt. as fertilized increased 50 to 150 ppm, while other nutrients were not significantly affected. Media EC increased with time and fertilizer concentration, with EC in all media fertilized with 250 ppm N exceeding 4.5 dS m-1 at the final harvest.

scholarly journals Solution Electrical Conductivity and Ratio of Nitrate to Other Nutrients Affect Accumulation of Nitrate in Hydroponic Lettuce

HortScience ◽  
2003 ◽  
Vol 38 (2) ◽  
pp. 222-227 ◽  
Author(s):  
Martin P.N. Gent
Keyword(s):  
United States ◽  
Electrical Conductivity ◽  
Stepwise Regression ◽  
Leaf Tissue ◽  
Dry Weight ◽  
High Irradiance ◽  
Tissue Composition ◽  
Nitrate Supply ◽  
N Treatment ◽  
Leaf Nitrate

Solution electrical conductivity (EC) and the supply of nitrate in proportion to other elements (nitrate supply ratio) should effect tissue composition of lettuce (Lactuca sativa L.) grown in hydroponic solution. These parameters were varied in several series of successive plantings in greenhouses in the northeast United States. In 1996, when the treatments differed only in EC, 0.65 and 0.9 dS·m-1, but not in nitrate supply ratio, leaf tissue had more nitrate and total reduced-N and lettuce grew faster in the solution with higher EC. Over four series of plantings in 1997 and 1998, the nitrate supply ratio of a low-N treatment was only 60% of that for a high-N treatment, and EC was varied from 1.2 to 2.0 dS·m-1. In 1997 and 1998, tissue nitrate was lower in the low-N treatment only when EC was less than in the high-N treatment. However, under irradiance greater than 10 MJ m-2 per day, the lower EC also slowed growth. Stepwise regression over data from all experiments showed leaf nitrate was primarily a function of EC, and a term that described the interaction between irradiance and EC. Due to selective uptake by the plants, the ratio of elements in the recirculating solution differed from the ratio in which they were supplied. Under irradiance less than 10 MJ m-2 per day and solution EC greater than 1.5 dS·m-1, nitrate accumulated in solution to a concentration greater than expected from simple dilution of the concentrates. Tissue nitrate was also related to solution nitrate, increasing by 0.08-0.09 mg·g-1 dry weight per 1 mg·L-1 increase in solution nitrate. To prevent a rise in tissue and solution nitrate under low irradiance, both solution EC and nitrate supply ratio had to be reduced by about one-third, compared to the conditions required for rapid growth under high irradiance.

scholarly journals Effects of low light intensities at night on nitrate accumulation in lettuce grown on a recirculating nutrient solution

1993 ◽  
Vol 41 (1) ◽  
pp. 13-21
Author(s):  
E.G. Steingrover ◽  
J.W. Steenhuizen ◽  
J. Van Der Boon
Keyword(s):  
Nutrient Solution ◽  
Nitrate Concentration ◽  
Leafy Vegetables ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Negative Effects ◽  
Nitrate Accumulation ◽  
Light Intensities ◽  
Nutrient Film Technique ◽  
Nutrient Solutions

During winter, when light intensities are low, high nitrate concentrations often occur in leafy vegetables which are undesirable from the viewpoint of public health. The effects of low lighting during the night in combination with various nutrient solutions and solution temperatures on the nitrate concentration of lettuce cv. Panvit plants grown in a nutrient film technique system were studied. The experiment showed that lettuce heads could be grown during winter under glass with a nitrate concentration as low as 2900 mg/kg FW, which is much lower than the maximum permissible concentration for winter-grown lettuce in the Netherlands of 4500 mg/kg. The lowest nitrate concentration, without negative effects on yield or quality, was obtained by growing the crop on recirculating nutrient solutions with an initial ammonium:nitrate ratio of 0.25, with a change to a ratio of 1.0 for the last 2 weeks. The addition of chloride did not affect the nitrate concentration. Raising the temperature of the nutrient solution at night from 6 to 10 degrees C in combination with a minimum air temperature of 6 degrees stimulated growth, but also increased the lettuce nitrate concentration by an average of 360 mg/kg. Supplying light of a low intensity at a photon flux density of 27 micro mol m-2s-1 (400-700 nm) at night for up to 8 nights before harvest did not further reduce the nitrate concentration on a FW basis because the dry matter percentage increased.

scholarly journals Nitrate concentration in lettuce leaves depending on photosynthetic photon flux and nitrate concentration in the nutrient solution

2011 ◽  
Vol 29 (4) ◽  
pp. 548-553 ◽  
Author(s):  
Nilton Nélio Cometti ◽  
Madlles Q Martins ◽  
Cintia Aparecida Bremenkamp ◽  
José Arcanjo Nunes
Keyword(s):  
Nutrient Solution ◽  
Nitrate Concentration ◽  
Nitrate Solution ◽  
Light Availability ◽  
Dry Mass ◽  
Photon Flux ◽  
The European Union ◽  
Photosynthetic Photon Flux ◽  
Nitrate Accumulation ◽  
Growing Period

The nitrate accumulation in plant tissues can occur due to low light availability. However, published studies have not linked nitrate accumulation to photosynthetic photon flux (PPF) measured during the growing period. This study aimed to evaluate the effect of the reduction of photosynthetic photon flux and the concentration of nitrate in the nutrient solution on agronomic characteristics and accumulation of nitrate in lettuce grown in hydroponics. The trial design was entirely randomized in a factorial scheme (4 x 2) with three repetitions, and four shading levels: 0, 30, 50, and 80% and two nitrate levels in nutrient solution: 5 and 10 mmol L-1. The dry matter production decreased directly and linearly with the reduction of light. The lowest level in nitrate solution also led to reduction in dry mass yield. The maximum accumulation of nitrate reached 966.3 mg kg-1 fresh mass, with PPF of 118 μmol/m²/s and 140 mg L-1 of N-NO3-1 (below the maximum levels recommended by the European Union), and the minimum of 200 mg kg-1 with PPF of 455 μmol/m²/s and 70 mg L-1 of N-NO3-1 in the nutrient solution. The reduction of nitrate in the nutrient solution from 140 to 70 mg L-1 led to the reduction of nitrate accumulation in shoots, but also caused a decrease in the production of phytomass of shoots, as well as reduced leaf area significantly.

Phosphate biogeochemical barrier for uranium in situ immobilization in an aquifer nearby sludge repository

2021 ◽  
Author(s):  
Grigory Artemiev ◽  
Alexey Safonov ◽  
Nadezhda Popova
Keyword(s):  
Essential Elements ◽  
Ion Concentration ◽  
Soluble Form ◽  
High Concentration ◽  
Rapid Reduction ◽  
Near Surface ◽  
Nitrate Ions ◽  
Uranium Migration ◽  
Storage Facilities

<p>Uranium migration in the oxidized environment of near-surface groundwater is a typical problem of many radiochemical, ore mining and ore processing enterprises that have sludge storage facilities on their territory. Uranium migration, as a rule, occurs against a high salt background due to the composition of the sludge: primarily, nitrate and sulfate anions and calcium cations. One of the ways to prevent the uranium pollution is geochemical or engineering barriers. For uranium immobilization, it is necessary to create conditions for its reduction to a slightly soluble form of uraninite and further mineralization, for example, in the phosphate form. An important factor contributing to the rapid reduction of uranium is a in the redox potential decreasing and the removal of nitrate ions, which can be achieved through the activation of microflora. It should be added that phosphate itself is one of the essential elements for the development of microflora. This work was carried out in relation to the upper aquifer (7-12 m) near the sludge storage facilities of ChMZ, which is engaged in uranium processing and enrichment. One of the problems of this aquifer, in addition to the high concentration of nitrate ions (up to 15 g / l), is the high velocity of formation waters.<br>In laboratory conditions, the compositions of injection solutions were selected containing sources of organic matter to stimulate the microbiota development and phosphates for uranium mineralization. When developing the injection composition, special attention was paid to assessing the formation of calcite deposits in aquifer conditions to partially reduce the filtration parameters of the horizon and reduce the rate of movement of formation waters. This must be achieved to ensure the possibility of long-term deposition of uranium and removal of nitrate. The composition of the optimal solution was selected and in a series of model experiments the mineral phases containing the lowest hydrated form of the uranium-containing phosphate mineral meta-otenite were obtained.<br>In situ mineral phosphate barrier Formation field tests were carried out in water horizon conditions in a volume of 100m3 by injection of an organic and phosphates mixture. As a result, at the first stage of field work, a significant decreasing nitrate ion concentration, and reducing conditions formation coupled with the dissolved uranium concentration of decreasing were noted.</p>

scholarly journals Two years of online measurement of fine particulate nitrate in the western Yangtze River Delta: influences of thermodynamics and N<sub>2</sub>O<sub>5</sub> hydrolysis

2018 ◽  
Vol 18 (23) ◽  
pp. 17177-17190 ◽  
Author(s):  
Peng Sun ◽  
Wei Nie ◽  
Xuguang Chi ◽  
Yuning Xie ◽  
Xin Huang ◽  
...  
Keyword(s):  
Diurnal Variation ◽  
Yangtze River ◽  
Nitrate Concentration ◽  
Yangtze River Delta ◽  
River Delta ◽  
Water Soluble ◽  
Online Measurement ◽  
High Concentration ◽  
Soluble Ions ◽  
Water Soluble Ions

Abstract. Particulate nitrate contributes a large fraction of secondary aerosols. Despite understanding of its important role in regional air quality and global climate, long-term continuous measurements are rather limited in China. In this study, we conducted online measurement of PM2.5 (particulate matter with diameters less than 2.5 µm) nitrate for 2 years from March 2014 to February 2016 using the Monitor for AeRosols and Gases in ambient Air (MARGA) in the western Yangtze River Delta (YRD), eastern China, and investigate the main factors that influenced its temporal variations and formation pathways. Compared to other sites in China, an overall high concentration of particulate nitrate was observed, with a mean value of 15.8 µg m−3 (0.5 to 92.6 µg m−3). Nitrate on average accounted for 32 % of the total mass of water-soluble ions and the proportion increased with PM loading, indicating that nitrate is a major driver of haze pollution episodes in this region. Sufficient ammonia drove most nitrate into the particle phase in the form of ammonium nitrate. A typical seasonal cycle of nitrate was observed, with the concentrations in winter on average 2 times higher than those in summer mainly due to different meteorological conditions. In summer, the diurnal variation of particulate nitrate was determined by thermodynamic equilibrium, resulting in a much lower concentration during daytime despite a considerable photochemical production. Air masses from the polluted YRD and biomass burning region contributed to the high nitrate concentration during summer. In winter, particulate nitrate did not reveal an evident diurnal variation. Regional transport from northern China played an important role in enhancing nitrate concentration. A total of 18 nitrate episodes were selected to understand the processes that drive the formation of high concentration of nitrate. Rapid nitrate formation was observed during the pre-episode (the day before nitrate episode day) nights, and dominated the increase of total water-soluble ions. Calculated nitrate from N2O5 hydrolysis was highly correlated to and accounted for 80 % of the observed nitrate, suggesting that N2O5 hydrolysis was a major contributor to the nitrate episodes. Our results suggested that rapid formation of nitrate could be a main cause for extreme aerosol pollution events in the YRD during winter, and illustrated the urgent need to control NOx emission.

Preparation of Silicalite-1 Membranes on α-Al2O3 Tubes and its Concentration Performance of Low Ethanol/water Mixtures

2012 ◽  
Vol 608-609 ◽  
pp. 1337-1341
Author(s):  
Hong Liang Chen ◽  
Ji Song Yang ◽  
Yan Wang ◽  
Hui Ying Li ◽  
Xin Xin Li ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Solution Concentration ◽  
High Concentration ◽  
Separation Selectivity ◽  
Naoh Solution

Silicalite-1 membranes were successfully synthesized on α-Al2O3 tubes by in-situ hydrothermal synthesis after filling the tubes with water and glycerol mixtures, and all the membranes show high concentration performance towards ethanol/water mixtures after pretreating tubes with different NaOH solution. The results show that the flux enhances with the enhancement of NaOH solution concentration, but the separation selectivity decreases with the enhancement of NaOH solution concentration. After pretreating the α-Al2O3 tubes with different NaOH solution, the weight of all the α-Al2O3 tube decreases, but the Si/Al ratio increases, which shows that suitable pretreatment of α-Al2O3 is useful for improving the hydrophobicity of silicalite-1 membranes.

scholarly journals Inmobilización y retención nutrimental en aserrín de pino como sustrato agrícola.

2019 ◽  
Vol 37 (3) ◽  
pp. 261
Author(s):  
Joel Pineda Pineda ◽  
Felipe Sánchez del Castillo ◽  
Esaú Del Carmen Moreno Pérez ◽  
Luis Alonso Valdez Aguilar ◽  
Ana María Castillo González ◽  
...  
Keyword(s):  
Nutrient Solution ◽  
Solution Concentration ◽  
Particle Sizes ◽  
Similar Concentration ◽  
Volcanic Tuff ◽  
Pine Sawdust ◽  
Low Concentrations ◽  
Growing Medium ◽  
Leachate Water ◽  
Main Substrate

Pine (Pinus sp.) sawdust has been used as a growing medium for the cultivation of vegetables and ornamentals. In the present work the objective was to assess the immobilization or retention of N, P, K, and Ca in pine sawdust as the main substrate component by applying Steiner nutrient solution at different concentrations (20, 30 and 40 meq L-1). We used uncomposted sawdust, alone or in mixtures (70/30, v/v) with volcanic tuff of different particle sizes (fine ≤ 3 mm, medium 3-6 mm, and coarse 6-12 mm). For two months, leachate was collected daily, and every 10 days, the average concentrations of N, P, K, and Ca, as well as pH and electrical conductivity (EC) were measured. The effect of the interaction substrate × nutrient solution concentration on N, P, K and Ca in the leached water was observed. These nutrients increased in concentration in the leachate water in accord with the nutrient solution concentration and as the diameter of volcanic tuff particles diminished. Irrigation with 20 meq L-1 (2 dS m-1) concentration of nutrient solution reduced the concentration of N, P, K, and Ca in leached water below its concentration in the supplied nutrient solution, while irrigation with 30 or 40 meq L-1 (2 or 4 dS m-1) resulted in similar concentration in leached water up to 20 or 30 dat, but at 40 dat, concentration of these nutrients in the leached water was higher. Immobilization of N and P, K, and Ca retention in the sawdust substrate occurred during the first 40 ddt, related to an increase in pH (up to 8.6), a decrease in EC (until 0.5 dS m-1) and low concentrations of N, P, K, and Ca in the leached water.

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