Increase In Concentration Of NO3 Research Articles

Effects of NO3– and SO42– Ions on the Coupled Reaction–Extraction–Crystallization Process of MgCl2 and CO2

The effects of NO3– and SO42– ions on the H+ concentration in organic phase and crystal morphology of solid product nesquehonite (MgCO3·3H2O) in the coupled reaction–extraction–crystallization process were investigated. During the coupled process, the H+ concentration in organic phase increased with the increase in concentration of NO3– ions and decreased with the increase in concentration of SO42– ions, indicating that NO3– ions promoted the carbonization of MgCl2 while SO42– ions inhibited the same. The rodlike MgCO3·3H2O crystals became short and thick in the presence of both NO3– and SO42– ions. Energy-dispersive X-ray spectroscopy (EDS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and molecular dynamic simulation were used to clarify the mechanism by which impurity ions modified the structure. The results indicated that the NO3– and SO42– anions could be selectively adsorbed on the top facet (011) of MgCO3·3H2O, preventing the growth of crystal surfaces, which results in the d...

The effect of different tillage and residue management practices on soil characteristics, inorganic N dynamics and emissions of N2O, CO2 and CH4 in the central highlands of Mexico: a laboratory study

Conservation agriculture in its version of permanent raised bed planting with crop residue retention increases yields and improves soil characteristics, e.g. aggregate distribution, organic matter content, so it remained to be seen how greenhouse gas emissions and dynamics of C and N might be altered. The objective of this study was to investigate how conservation agriculture with permanent raised beds, tied ridges, i.e. dykes within the furrows to prevent water run-off, and residue retention affected greenhouse gas emissions. A field experiment was started in 1999 comparing permanent and conventionally tilled raised beds with different residue management under rain fed conditions. Soil was characterized and emissions of CH4, N2O and CO2 and dynamics of NH4+, NO2− and NO3− were monitored in a laboratory experiment. The crop and tied ridges had no effect on soil characteristics and dynamics of C and N. Tilled beds reduced the water holding capacity (WHC) 1.1 times and increased conductivity 1.3 times compared to soil under nontilled beds with retention of all crop residues. The WHC, organic C, soil microbial biomass and total N were ≥1.1 larger in soil from nontilled beds where the crop residue was retained compared to where it was removed after only 6 years. The emission of CO2 was 1.2 times and production of NO3− 1.8 times larger in nontilled beds where the crop residue was retained compared to where it was removed. The CO2 emission was 1.2 times and the emission of N2O after 1 day 2.3 times larger in soil under tilled beds compared to nontilled beds with full residue retention, while the increase in concentration of NO3− was 0.05 mg N kg−1 soil in the former and 2.38 in the latter. We found that permanent raised bed planting with crop residue retention decreased emissions of N2O and CO2 compared to soil under conventionally tilled raised beds. Production of NO3− is larger in soil with permanent raised bed planting with crop residue retention compared to conventionally tilled raised beds.

Influence of nitrate level on nitrate assimilation in tomato (Lycopersicon esculentum) plants under saline stress

This experiment was conducted to study the effect of salinity and different NO3– concentrations on NO3– uptake, transport, and reduction. To avoid the significant effect of plant size, the main difference from other studies was the short time period of treatment application. Tomato plants (Lycopersicon esculentum Mill. 'Asun') were grown for 11 d in half-strength Hoagland solution (with 7 mmol/L NO3–) in a growth chamber under controlled conditions. After that, the different NO3– treatments were 0.5, 2, and 4 mmol/L NO3–, and saline treatments consisted of two levels of NaCl: 0 (control) and 75 mmol/L. Under control conditions, an increase in NO3– concentration in the nutrient solution resulted in greater NO3– uptake, NO3– xylem flux, NO3- concentrations in tissues, and leaf and root nitrate reductase activity. However, when plants were exposed to salinity for a short period of time and the plant size or the shoot/root ratio was not an additional factor affecting the physiological parameters, the NO3– concentration in the solution slightly affected the different steps of NO3– assimilation.Key words: nitrate assimilation, nitrate reductase activity, nitrogen, salinity, tomato, Lycopersicon esculentum.

Effects of surface soil removal on dynamics of dissolved inorganic nitrogen in a snow-dominated forest.

To clarify the effect of vegetation and surface soil removal on dissolved inorganic nitrogen (N) dynamics in a snow-dominated forest soil in northern Japan, the seasonal fluctuation of N concentrations in soil solution and the annual flux of N in soil were investigated at a treated site (in which surface soil, including understory vegetation and organic and A horizons, was removed) and control sites from July 1998 to June 2000. Nitrate (NO3) concentration in soil solution at the treated site was significantly higher than that of the control in the no-snow period, and it was decreased by dilution from melting snow. The annual net outputs of NO3 from soil at the treated site and control sites were 257 and –12 mmol m year, and about 57% of the net output at the treated site occurred during the snowmelt period. NO3 was transported from the upper level to the lower level of soil via water movement during late autumn and winter, and it was retained in soil and leached by melt water in early spring. Removing vegetation and surface soil resulted in an increase in NO3 concentration of soil solution, and snowmelt strongly affected the NO3 leaching from treated soil and the NO3 restoration process in a snow-dominated region.

Interactive effects of nitrate and long-term waterlogging on growth, water relations, and gaseous exchange properties of maize (Zea mays L.)

The interactive effect of additional amount of NO3-N and long-term waterlogging on maize was studied in glasshouse conditions. Forty-two-day-old plants were subjected to continuous flooding for 21 days at three different NO3-N regimes (196, 294 and 392 mg N kg−1 soil). Shoot fresh mass and leaf area of waterlogged plants reduced significantly at two higher NO3 regimes. Leaf water potential was generally decreased, whereas osmotic potential increased in all waterlogged plants but much reduction in leaf water potential was found at the highest external NO3 regime. Leaf turgor potential decreased due to waterlogging but this decrease progressed with increase in external NO3 concentration. Chlorophylls ‘a’ and ‘b’ increased in non-waterlogged plants with increase in NO3 concentration of the growth medium, but these two pigments decreased significantly due to waterlogging particularly at the two higher NO3 regimes. Chlorophyll a/b ratio increased linearly in non-waterlogged plants with increase in external NO3 regimes but the ratio remained almost unchanged due to waterlogging. Waterlogging caused a reduction in net photosynthesis and stomatal conductance but no effect of additional amount of NO3 was observed on these two variables. Transpiration was also decreased as a result of waterlogging but a marked reduction in this variable was observed at the highest external NO3 concentration. Water-use efficiency increased with increase in external NO3 concentration in both waterlogged and non-waterlogged plants. Although waterlogging caused a reduction in substomatal CO2 concentration, it generally increased in both waterlogged and non-waterlogged plants due to supplementary NO3, particularly at its highest concentration. From these results, it is clear that supplementary NO3 in the growth medium of maize plants experiencing long-term waterlogging had injurious effect on growth.