Main Form Of Nitrogen Research Articles

Effects of Gas Flaring on Soil Fertility

This article, written by Technology Editor Dennis Denney, contains highlights of paper SPE 93666, "Impact of Gas Flaring on Soil Fertility," by R.E. Akpojivi, SPE, and P.E. Akumagba, SPE, Petroleum Training Inst., Effurun, prepared for the 2005 SPE Middle East Oil & Gas Show and Conference, Bahrain, 12-15 March. Gas flaring is used in Nigeria to dispose of associated gas. Low flare stacks bring the flare close to nearby vegetation and soil. This study investigated the effect of oil-sector gas-flaring activity on soil-fertility parameters. Introduction Gas flaring is the burning of natural gas and other petroleum hydrocarbons at flare stacks in oil fields during operation. The casing-head gas produced as associated natural gas during oil production varies in composition from location to location; however, the basic components include methane, ethane, propane, iso-butane, n-butane, iso-pentane, n-pentane, n-hexane, CO2, H2S, He, and N2. Modern technology and commercial opportunities have permitted industrialized nations, which often flared natural gas during the early history of oil production, to now process it for commercial sale or reinjection into the reservoirs. However, several sub-Saharan African nations including Nigeria still use gas flaring as a method to dispose of associated gas during oil-sector operations, ostensibly because gas infrastructure is extremely low. For example, despite efforts to expand the gas-to-liquid industry in Nigeria, companies flared [667 Bscf of natural gas at 176 locations in 2002, according to the U.S. Energy Information Agency, Dept. of Energy]. This gas flaring represents [49%] of the total gas produced in Nigeria in 2002. Flaring of associated gas releases emissions rich in carbon, nitrogen, and sulfur oxides and soot. These acid gases are carried downward as acid deposition (wet and dry depositions) onto vegetation, soil, and water bodies in communities close to the flare sites. Also, intense heat and continuous illumination are associated with gas flaring. The low height of flare stacks ensures local pollution at ground level and nearby dry deposition, as well as close heating of surrounding vegetation and soil. Likely acid deposition and intense heat from gas flares are likely to harm the fertility of the surrounding soils. The obvious signs are the poor vegetation growth and scorched soils around gas-flare locations. Acid deposition decreases the soil pH. However, the effect of acid deposition on a particular soil ecosystem is influenced by such factors as acid sensitivity, neutralization capability, concentration and composition of acid reaction products, and the amount of acid added to the system. The basic cations (Ca2+, Mg2+, and K+) are replaced by hydrogen ions or soluble metals and are lost through leaching. Increased acidity reduces activity of soil microorganisms sensitive to low pH, thus decreasing decomposition of plant residues and the recycling of essential plant nutrients. The concentration of trace-metal ions in soil solution increases (including aluminium, copper, iron, zinc, boron, manganese, chromium, and nickel) to levels that may be phytotoxic. Phosphorus compounds in the soil become mostly aluminum and iron phosphates, resulting in a reduced availability of plant phosphorus. Plant uptake of molybdate is reduced. Nitrification by the main autotrophic genera involved (Nitrosononas and Nitrobacter) is inhibited; thus, NH4+ is the main form of nitrogen taken up by plants instead of NO3−. There is reduced symbiotic nitrogen fixation by legumes, except the Rhizobium strain, which is acid tolerant.

Nitrogen Form Effects on Yield and Nitrogen Uptake of Rice Crop Grown in Aerobic Soil

As an alternative production strategy, the cultivation of rice under upland condition is increasing in the areas where fresh water resource is limited during growing season. The main form of nitrogen (N) taken up by rice roots is shifted from ammonium (NH4) in flooded paddy soil to nitrate () in upland soil. A pot experiment was conducted in order to study the influence of to ratio on the yield and uptake of N by rice (Oryza sativa L.) grown under upland conditions. The sandy-loam soil (85-kg) used to fill each pot was mulched by semi-decomposed straw, and a total 4.8 g N per pot was supplied as a fertilizer topdressing at five ratios of -N/-N (0/100, 25/75, 50/50, 75/25, and 100/0). In comparison to provision of alone, supply of as the only N source produced higher number of effective ears and average weights of 1000 grains, but reduced the grain numbers in each effective ear. The total uptake of N and biomass yield per pot were 2.206 and 182.5 g from applying only , and 2.067 and 163.7 g from -N alone, respectively, while they reached 2.894 and 217.9 g when both forms of N were supplied in equal amounts. Soil -N concentration was constantly maintained at the range of 2–6 mg kg−1 during the vigorous growing period when the supply was less than 75% indicating little risk of N fertilization induced NO3 pollution in the rice-cultivated upland soil. The rice crop did not show a significant preference to the form of or alone. Provision of the dual N sources enhanced the growth and N use efficiency by rice crop cultivated in the upland soil.

Effect of total ammonia nitrogen concentration and pH on growth rates of duckweed ( Spirodela polyrrhiza)

The use of duckweed in domestic wastewater treatment is receiving growing attention over the last few years. Duckweed-based ponds in combination with anaerobic pre-treatment may be a feasible option for organic matter and nutrient removal. The main form of nitrogen in anaerobic effluent is ammonium. This is the preferred nitrogen source of duckweed but at certain levels it may become inhibitory to the plant. Renewal fed batch experiments at laboratory scale were performed to assess the effect of total ammonia (NH 3+NH + 4) nitrogen and pH on the growth rate of the duckweed Spirodela polyrrhiza. The experiments were performed at different total ammonia nitrogen concentrations, different pH ranges and in three different growth media. The inhibition of duckweed growth by ammonium was found to be due to a combined effect of ammonium ions (NH + 4) and ammonia (NH 3), the importance of each one depending on the pH.

Chemical characteristics of Aetoliko lagoon, Greece, after an ecological shock

A series of chemical parameters were studied in the water, particulate matter and sediments of Aetoliko lagoon, a wetland in western Greece, after an ecological impact at the end of November 1990, which resulted in massive death of fish. The permanent anoxic conditions in the deeper water layer of the lagoon, with the simultaneous formation of hydrogen sulfide, are the main characteristics of the system. The dramatic reduction of the dissolved oxygen in the surface water which was substituted by the hydrogen sulfide of the near bottom water layer caused the sudden death of organisms. This phenomenon also affected the nutrients. Ammonia was the main nitrogen form; phosphates and silicates were concentrated in near bottom waters, and the concentrations of nitrates and nitrites were much lower in December than 3 months later in the surface waters. The behaviour of trace metals also indicated that in the extraordinary conditions studied, the main mechanisms of transport of metals among the main phases of the system (dissolved-particulate-sediments) were severely disturbed.

Nitrate and ammonium uptake by wheat seedlings as affected by salinity and light

Abstract Nitrate (NO3‐) and ammonium (NH4+) are the two main forms of nitrogen (N) taken up by plants. Several environmental factors affect the uptake of N. This work was undertaken to study the induction of NO3‐ and NH4+ transport systems in wheat (Triticum aestivum L.) roots as affected by salinity and light. Wheat seedlings were germinated in sterilized vermiculite and plants were grown in a growth chamber under controlled conditions for eight days with a nutrient solution without N, and with or without sodium chloride (NaCl). Uptake rates of NO3% NH4+, or NH4++ NO3‐ were calculated by measuring the disappearance of N from the solutions. The NO3‐ uptake developed with time, either through induction or activation. Salinity pretreatments increased net uptake rates of NO3‐ and NH4 +, suggesting that plants were in a higher N‐deficient status when grown in saline conditions. Light decreased initial NO3”; uptake but had little effect on initial NH4+ uptake.

Nitrogen pollution of leachate at a sea-based solid waste disposal site and its nitrification treatment by immobilized acclimated nitrifying sludge

It was found that changes in the nitrogen concentration of leachate from the Osaka North Port sea based disposal site were closely related to the way in which dumping was carried out. The nitrogen concentration of the leachate was low due to the low nitrogen content and slow nitrogen dissolution rate of materials dumped previously in the landfill. The dumping of incinerator ash, noncombustible garbage, waterworks sludge and incinerated ash from sewage sludge were followed, and it was found that they caused a sharp increase in nitrogen concentration in the leachate. The main nitrogen form of leachate was NH 4-N, and its concentration reached 50 mg/ l after 6 years of landfilling. Successful nitrification treatment of leachate (more than 80% nitrification) was possible by using polyvinyl alcohol immobilized acclimated marine nitrifying sludge with an NH 4-N loading rate of 2.9 mg-NH 4-N/g-pellets/d. Low NO 2-N was detected throughout the continuous nitrification experiments, so the rate limiting step in the nitrification treatment was revealed to be a nitrification step (NH 4 +→NO 2 −). The addition of inorganic carbon to the test leachate enabled us to perform nitrification treatment even with a high NH 4-N loading rate. Dolomite limestone was shown experimentally to be able to replace inorganic chemicals.

N and P Distribution in Lake Kinneret (Israel) with Emphasis on Dissolved Organic Nitrogen

Lake Kinneret (Israel) belongs to the warm monomictic type. Its high nitrogen input is compensated by denitrification during the anoxic period, and the concentration of phosphate is severely limited by chemical equilibria. However, a dense bloom of dinoflagellates develops in winter-spring. Distribution of N and P shows that the lake water is the largest pool of N whereas sediments are the main reservoir of P. Seasonal and vertical fluctuations of dissolved organic nitrogen (DON), the main form of nitrogen, are described. Autolysis of cells at the end of the bloom release large amounts of DON in the upper layers. However, another fraction is sedimented and remains unchanged during the anoxic period. At the next turnover, the enhancement of oxidative process generates the production of DON. It is generally ammonified rapidly. Delay in ammonification and the resulting accumulation of DON, may retard the Peridinium bloom, probably because of the chelating effect of DON.