Nitrate and Nitrogen Oxides: Sources, Health Effects and Their Remediation

Abstract

Increased use of nitrogenous (N) fertilizers in agriculture has significantly altered the global N-cycle because they release nitrogenous gases of environmental concerns. The emission of nitrous oxide (NO) contributes to the global greenhouse gas accumulation and the stratospheric ozone depletion. In addition, it causes nitrate leaching problem deteriorating ground water quality. The nitrate toxicity has been reported in a number of studies showing the health hazards like methemoglobinemia in infants and is a potent cause of cancer. Despite these evident negative environmental as well as health impacts, consumption of N fertilizer cannot be reduced in view of the food security for the teeming growing world population. Various agronomic and genetic modifications have been practiced to tackle this problem. Some agronomic techniques adopted include split application of N, use of slow-release fertilizers, nitrification inhibitors and encouraging the use of organic manure over chemical fertilizers. As a matter of fact, the use of chemical means to remediate nitrate from the environment is very difficult and costly. Particularly, removal of nitrate from water is difficult task because it is chemically non-reactive in dilute aqueous solutions. Hence, the use of biological means for nitrate remediation offers a promising strategy to minimize the ill effects of nitrates and nitrites. One of the important goals to reduce N-fertilizer application can be effectively achieved by choosing N-efficient genotypes. This will ensure the optimum uptake of applied N in a balanced manner and exploring the molecular mechanisms for their uptake as well as metabolism in assimilatory pathways. The objectives of this paper are to evaluate the interrelations which exist in the terrestrial ecosystems between the plant type and characteristics of nutrient uptake and analyze the global consumption and demand for fertilizer nitrogen in relation to cereal production, evaluate the various methods used to determine nitrogen use efficincy (NUE), determine NUE for the major cereals grown across large agroclimatic regions, determine the key factors that control NUE, and finally analyze various strategies available to improve the use efficiency of fertilizer nitrogen.

In vivo and ex vivo impact of nutritional xenobiotics – acrylamide and sodium nitrates – on plasma antioxidant properties

“…The measurement of SH concentrations is also used in scientific research to evaluate the oxidative damage of proteins in a variety of pathological conditions [34,35]. Both ACR and SN (V) and (III) are present in many food products, and the thermal processing of food increases the content of these compounds [20,24,36]. Although SN (V) and (III) are used in the food industry as preservatives (antioxidants), represented by the symbols E251 and E250, respectively [37], their contribution to the intensification of OS is also indicated [38].…”

“…It is known that the antioxidant capacity changes under exposure to various xenobiotics, as well as those derived from foods [21]. The general toxic effects of ACR and SN (V) and (III), and nutritional questionnaires on the intake of these substances in the diet are relatively numerous and well-known [20,22,23,24], but there is still a lack of data evaluating the impact of these compounds on the total cellular pool of free thiols in blood plasma. The aim of this study was to estimate the influence of ACR and SN (V) and (III), derived from the diet, on the total pool of free thiols in blood plasma in young healthy people.…”

Azotobacter: A potential bio-fertilizer for soil and plant health management

“…Azotobacter is able to convert atmospheric nitrogen to ammonia, which in turn is taken up and utilized by the plants ( Prajapati et al, 2008 ). Such bacteria are immensely resistant to oxygen during nitrogen fixation due to respiration protection of nitrogenase ( Hakeem et al, 2016 ). In addition to the respiratory protection there also exist hydrogenase uptake as well as switch on–off mechanisms for the protection of nitrogenase enzyme from oxygen ( Chhonkar et al, 2009 ).…”

Microorganisms and Their Metabolic Capabilities in the Context of the Biogeochemical Nitrogen Cycle at Extreme Environments

“…The abusive use of fertilizers and pesticides has significantly altered the global N-cycle because of the release of nitrogenous gases due to the metabolic activities of soil microbes. As mentioned, the emission of nitrous oxide (N 2 O) contributes to the global greenhouse gas accumulation and the stratospheric ozone depletion [ 47 , 162 , 163 ]. These connections have been explored in detail mainly in forest ecosystems [ 164 ], pasture soils [ 165 , 166 ], and standard agricultural soils or agricultural soils suffering dramatical pH changes [ 164 , 165 , 166 , 167 , 168 , 169 , 170 ].…”