EIA Study- Final Report-May 10 - UNDP

Environmental Impact Assessment
Khan Younis Wastewater Treatment Plant May 2010
Nitrate:
90 per cent of Gaza's water samples were found to contain nitrate concentrations that
were between two and eight times higher than the limit recommended by the World
Health Organization (WHO). Organic fertilizers and wastewater are the main causes of
the nitrate contamination in the groundwater, followed by sewage sludge and artificial
fertilizers. This was revealed by the isotope ratios of nitrogen (15N/14N) and oxygen
(18O/16O) in the nitrate. Isotopes are variations of the same chemical element that have a
different number of neutrons in their nuclei. 18O and 15N are stable, i.e. non-radioactive,
isotopes that are heavier than "normal" oxygen (16O) or nitrogen (14N) and can therefore
be measured using a mass spectrometer. The lower 15N nitrogen isotope values in the
sewage sludge indicate that the nitrate in the Gaza groundwater comes primarily from
manure used as fertilizer. Between 2001 and 2007 samples from 115 municipal wells and
50 private wells have been taken on seven occasions. Nitrate concentrations of between
31 and 452 milligrams per liter were detected. Only 10 of the 115 municipal wells
examined were found to have a nitrate level below the WHO guideline value. The
situation with the private wells was equally serious: apart from three, all the wells were
found to have nitrate levels that were between five and seven times higher than the WHO
recommendations.
Figure 5.6: Average nitrate concentrations in groundwater in Khan Younis Governorate for year 2007.
The nitrate concentration in the area surrounding both the wastewater treatment plant and
the suggested infiltration basin exceed the level recommended by the WHO. As shown
by the nitrate level groundwater in Khan Younis governorate, figure 5.6, it is more than
100 mg per liter.
SOGREAH/UG CONSULTANTS 59