International Rainwater Catchment Systems Conference
Catchment: An Answer to the Water Scarcity of the Next Millennium."
Petrolina, Brazil - July 1999
Section 12: Posters
Nitrogen in the Agha Jari Formation of the Bisheh Zard Basin: A Dilemma
Sayyed Ahang Kowsar & Ali Reza Yazdian
Fars Research Center
Nitrogen deficiency ranks right behind water as the second
most constraint to crop production in the coarse - loamy sand of the Gareh
Bygone Plain (GBP) in southern Iran. As better resource utilization is
essential to wise energy management, contrary to the reported cases, surface
water pollution by N maybe a boon in the GBP. The Agha Jari Formation, in which
the Bisheh Zard Basin (BZB) that supplies the GBP with floodwater has been
formed, contains NO-3 and NH+4 in its sandstone, siltstone and marl components.
Therefore, it is expected that some of the geologic N dissolved in floodwater,
and carried by the suspended load, reach the watertable, and also supply the
plants coming in contact with the water and/or sediment.
To study the origin of N in the BZB, and investigate the
fate of the dissolved and adsorbed N as it travels form the watershed to the
watertable, 13 rock samples, 7 floodwater samples and 71 soil samples were
collected and analyzed for NO-3and NH+4. The NO-3concentration was higher than
that ofNH+4 in all of the samples: 77 ppm vs. 38 ppm in the floodwater; 47 ppm
vs. 20 ppm in the soil; and 22 ppm vs. 12 ppm in the rocks. Assuming the mean
annual inflow of the GBP floodwater spreading system in 10 million m3,
the system receives 370 metric tons of NH+4 and 770 metric tons of NO-3 which
exceed the N requirement of the small grains if this system is planted to them.
As the U.S. Environmental Protection Agency has declared the
maximum contaminant level of NO-3 - N at 10mg per liter (44.4 mg NO-3 per
liter), and its concentration in floodwater in the GBP is 1.73 fold that
amount, purification of the water is in order. High NO-3 consuming plant
species might offer an environmentally friendly technology to decrease the
deleterious effects of N containing floodwater. The study concerned with the
flow of N towards groundwater will be reported later.
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