Background and purpose: This study was undertaken to examine the reversibility of renal injury in the male New Zealand white rabbits, subsequent to a 90-days exposure to uranyl Nitrate (UN) in the drinking water. Animals were exposed for 90 days to uranyl Nitrate in their drinking water (24 or 500mg/l).  The control group was given municipal tap water.Materials and Methods: The biomarkers of kidney function measured in this study includedb-2 micro globulin (marker of tubular), micro albumin (marker of glomerular) and the marker for cell toxicity was catalase.Results: Excretion of b-2 micro globulin was to be significantly different and was correlated with uranium intake for rabbits in early weeks. Microalbuminuria was found to be significantly different but this different was within normal range. Catalasuria was not significantly different in this study.Conclusion: These results suggest that chronic ingestion of uranium in the drinking water affects kidney function and is related to the proximal tubule, rather than glomerul.

Nitrogen is considered as an essential nutrient for plants and could be taken up in large amounts by plants. Nitrogen fertilizers are known to have beneficial effects when added to pistachio and other fruit trees. But the nitrogen assimilation of Pistacia species in response to salinity, including uptake and NO-3 reduction, has not been well understood. In this study, Nitrate reductase activity, total amino acids, Nitrate, calcium and sodium accumulation were evaluated in seedlings of Pistacia vera L. ̒ Badami Zarand̕ in response to sodium chloride (0, 75, 150 mm) and calcium Nitrate (0, 10, 15 mm). Results showed that by increasing the level of salinity, Nitrate reductase activity in leaves and the concentration of Nitrate, total amino acids and calcium (Ca2+) were reduced in the leaves and roots of P. Vera seedlings. Calcium Nitrate induced a significant increase in both the root and leaf Nitrate and total amino acids or Nitrate reductase activity in leaf under NaCl stress. Calcium Nitrate, also, significantly increased root/ leaf total amino acids ratio and decreased Na+/Ca2+, ratio in the roots. Results showed that salinity affects the Nitrate assimilation in P. Vera plants. Also, results suggest an efficient salt protective mechanism in P. Vera seedlings mediated by free total amino acids and calcium ions

Nitrate is one of the major sources of nitrogen for the growth of plants. It is taken up by plant roots and transported to the leaves where it is reduced to nitrite in the. The main objective of this research was to investigate stimulatory effects of sodium Nitrate, potassium Nitrate, ammonia and urea on the production/generation of the Nitrate reductase mRNA in Triticum aestivum plants. The plants were grown in standard nutrient solution for 21 days and then starved in a media without Nitrate for seven days. Starved plants were stimulated with various concentrations of sodium Nitrate, potassium Nitrate, ammonia and urea, and the expression of Nitrate reductase mRNA was analyzed by real-time PCR. Our results indicated that starvation caused significant decrease in the production of Nitrate reductase mRNA in the plant leaf. Sodium and potassium Nitrate were capable of restoring the production of Nitrate mRNA in a dose-dependent manner, since 50 mM of each produced the highest level of the mRNA. The stimulatory effect of potassium Nitrate was higher than sodium Nitrate, while ammonia and urea did not show such activity. At low concentrations, sodium Nitrate and potassium Nitrate caused significant increase in the Nitrate/nitrite mRNA production, whereas high concentrations of these salts suppressed the expression of this gene considerably.

Nitrate influx across the plasma membrane by NO3- transport systems named LATS and HATS. Low affinity transport systems (LATS) act at high levels of external NO3- (in mM level) but high affinity transport systems (HATS) act at low levels of external NO3- (in mM level). The members of the NRT2 gene family encode inducible high affinity Nitrate transporters (iHATS) that among them NRT2.1 and NRT2.2 genes both are involved in Nitrate uptake. It seems the role of NRT2.1 gene is more important than the other one. The activity of both genes also need the expression of another gene that so called NAR2. Therefore, in order to gain further insight into the mechanisms of Nitrate uptake by inducible high affinity transport systems, the transgenic Nicotiana plumbaginifolia which was transformed by AtNRT2.1 and NAR2 genes (were isolated from Arabidopsis thaliana) together with kanomycine resistance marker gene was used. The rate of Nitrate uptake in the medium containing different concentration of Nitrate (10, 25, 50, 75 and 100 mM) was studied in wild type and transgenic plants at hydroponic condition. The results revealed that almost in all different concentration of Nitrate in the medium, wild type plant absorbed the Nitrate with 2 to 3 hours delay. Whereas transgenic plants started to uptake the Nitrate immediately. On the other hand the rate of Nitrate uptake in transgenic plants was much higher than wild type plants at 10 and 25 mM concentrations Nitrate in the medium. By increase of Nitrate concentration in the medium (from 50 to 100mM) no significant difference in uptake in transgenic and wild type plants was observed. Furthermore, the results also showed that when the transgenic and wild type plant were grown in 50mM Nitrate in the medium in hydroponic condition, no significant difference on growth factors (root and shoot length, fresh weight and relative chlorophyll) was observed.

At the start of growing season, Nitrate concentration in soil is high. Therefore, during the autumn, organic N will be converted to inorganic N, and at this time, N fertilizer is added to soil. The optimum use of this amount of nitrogen will be useful. There fore, some wheat cultivars were studied in a serie of experiment using a hydroponic culture system for the Nitrate uptake and analysis. Seedlings were grown at two rates of Nitrates (0 and 1.0 mm) and were compared in a 26 day growth period. Results indicated that a significant difference exists between wheat cultivars for the Nitrate uptake. Atila and yavarous cultivars absorbing higher amount of Nitrate produced larger seedlings, compared to the falat, star and sarasari 11 cultivars which produced smaller seedling and took up lower amounts of Nitrate. According to difference among cultivars for seedling vigor, the results indicated that the first group including Atila, Chenalter, Sarasari 20, Yavarous, and Sarasari 11 had more physiological efficiency in Nitrate consumption. According to absorbed Nitrate, the amount of produced dry matter by the cultivars of this group was higher. On the whole we can say that genetic variation in Nitrate absorption among wheat cultivars is due to a modification in plant size and specifically the root system.

During the recent decades, the increasing trends in Nitrate ion concentration in ground water sources have meant more research to find effective procedures for the prevention of even more water contamination by nitrogen sources. In this study a pilot was designed to examine the application of biological method for eliminating Nitrate from the water of well No.903 of  ehrabad Airport, Tehran, Iran. Design, installation and running processes were done from April to November 2003. A fixed biological bed containing five-centimeter trunk pipes 16 mm in diameter were installed in the reactor and the system was operated with upflow current. Instead of Methanol, Acetic acid was used as the carbon source because of its easier acceptance by the public, lower price and availability as well as easier storage. The pilot was run in different hydraulic retention times from 48 h up to one hour. Considering economical, operational and maintenance factors, retention time of 2 h was determined to be optimum, in which 77% Nitrate removal was achieved. Considering a ratio of 2 for COD/N, inlet COD of about 140 mg/L and the optimum retention time, COD removal of about 80% is also accomplished in this process. The amount of nitrite concentration, pH values, COD and turbidity is also evaluated versus different hydraulic retention times.  

In the last few decades Nitrate contamination of groundwater has been concerned as one of the major environmental problems. Recent studies have established that the nitrogen (N) and oxygen (O) isotopes of Nitrate (NO3) can be used to trace nitrogen dynamics including identifying Nitrate sources and nitrogen transformation processes. Stable isotope ratios (δ 15N– NO3, δ 18O– NO3 and δ D-H2O) of groundwater samples were determined and used to identify contamination sources and transformation processes occurring in Varamin aquifer, Southeast Tehran, Iran with intense human activities. The approach is based on the fact that NO3 originating from different sources would exhibit different isotopic compositions. In addition, δ 18O– NO3 is more useful to identify Nitrate from atmospheric sources and nitrogen transformation processes. In the case study aquifer, the Nitrate concentration of groundwater was in the range of 0. 4 to 79. 59 mg/l with mean value of 25. 14 mg/l. The nitrogen and oxygen isotopic compositions of Nitrate in pore water extracts from the groundwater samples indicated at least two potential sources of Nitrate in Varamin Aquifer. These sources included human wastewater and animal wastes as well as soil N. The most common source of Nitrate contamination in groundwater is identified as wastewater. The significant process in the aquifer is the denitrification process occurred specially in the West and South West of Varamin aquifer.

Lettuce is one of the best accumulators of heavy metals and Nitrate between leafy vegetables. Through this research, it was tried to decreased cadmium absorption with humic acid (HA) and studies the effect of HA on the accumulation and metabolism of Nitrate. Plants were grown in the peat/perlite and irrigated with Hoagland solution with addition of cadmium (2 and 4 mg L-1) and HA (100 and 1000 mg L-1). Results showed that Cd in media increased Cd of leaves and decreased protein and fresh weight but it has not any effect on the N, P and Nitrate concentration and Nitrate reductase activity. With increasing concentration of HA, increasing in fresh weight, N, protein concentration and decreasing in Cd concentration in leaves was observed. Using of HA and Cd together in nutrient solution showed that HA decreased absorption of Cd. So toxic effect of Cd decreased on the physiological changes of lettuce and do not accumulate Nitrate in leaves, as well. More investigations should be done for using HA on the polluted soil for planting of lettuce.