Elevated nitrate levels in the groundwater of the Gaza Strip: Distribution and sources

• Published in: The Science of the total environment 2008-07, Vol.398 (1), p.164-174
• Main Authors: Shomar, Basem, Osenbrück, Karsten, Yahya, Alfred
• Format: Article
• Language: English
• Subjects: agricultural soils; Agrochemicals; Agronomy. Soil science and plant productions; animal manures; Animals; Applied sciences; Aquifers; Bacteria; Biological and medical sciences; Earth sciences; Earth, ocean, space; Effluents; Engineering and environment geology. Geothermics; Environmental Monitoring; Exact sciences and technology; Fertilizers; Fertilizers - analysis; Fundamental and applied biological sciences. Psychology; Gaza; Gaza Strip; Geochemistry; Groundwater; groundwater contamination; Groundwaters; Human wastes; Manure; Manure - analysis; Middle East; Monitoring; Natural water pollution; Nitrate; nitrate nitrogen; Nitrates; Nitrates - analysis; nitrogen content; Nitrogen Isotopes - analysis; Nitrogen/oxygen isotopes; Oxygen isotopes; Oxygen Isotopes - analysis; Pollutants; Pollution; Pollution, environment geology; Sewage - analysis; sewage sludge; Sludge; Soil (material); Soil - analysis; Soil and water pollution; soil chemistry; Soil science; Strip; Waste water; Water Pollutants, Chemical - analysis; water pollution; Water Supply - analysis; Water treatment and pollution; Wells
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2008.02.054

Seven years of monitoring groundwater in the Gaza Strip has shown that nitrate was and still is a major groundwater pollutant. The objectives of this research were to study the distribution of NO 3 − in the groundwater of the Gaza Strip and to identify the sources of NO 3 − in the Gaza aquifer system by assessing nitrogen and oxygen isotopes. The most recent samples collected in 2007 showed 90% of the wells having NO 3 − concentrations that are several times higher than the WHO standards of 50 mg/L. Potential NO 3 − source materials in Gaza are animal manure N, synthetic NH 4 based fertilizers, and wastewater/sludge. The average concentrations of N in the sludge, manure and soil of Gaza were 2.9%, 1% and 0.08%, respectively. The range in δ 15N of solid manure samples was + 7.5 to + 11.9‰. The range in δ 15N of sludge samples was + 4.6 to + 7.4‰, while four brands of synthetic fertilizers commonly used in Gaza had δ 15N ranging from + 0.2 to + 1.0‰. Sludge amended soil had δ 15N ranging from + 2.0 to + 7.3‰. For both δ 18O and δ 15N, the ranges of groundwater NO 3 − were − 0.1 to + 9.3‰ and + 3.2 to 12.8‰, respectively. No significant bacterial denitrification is taking place in the Gaza Strip aquifer. Nitrate was predominantly derived from manure and, provided δ 15N of sludge represents the maximum δ 15N of human waste, to a lesser extent from septic effluents/sludge. Synthetic fertilizers were a minor source.