[Nitrate contamination of the groundwater of the Akkar Plain in northern Lebanon].
The Akkar Plain in northern Lebanon covers an area of 130 km2 and is the second largest agricultural region in the country. It also borders the Mediterranean Sea (Figure 1). Groundwater supplies are the only source of drinking water in this region and there is no public drinking water network. This area has a population of about 75,000 inhabitants, who have depended on and used the water from these aquifers for many years, with no treatment, filtration or monitoring system in place. The inhabitants and farmers depend on groundwater supplies for crop irrigation and other uses. The plain provides ideal conditions for agriculture and the use of chemical fertilizers has been increasing. Over-fertilization, resulting in the application of excess nitrogen, and the lack of vegetation during the winter have disturbed the nitrogen cycle, leading to the pollution of groundwater supplies with high concentrations of nitrate. Nitrates seep slowly into the soil at a rate of about 0.5 to 1 meter per year until they reach the water table. However, tons of nitrogen are carried into the groundwater each year by runoff and infiltration. If a water source is found to be heavily contaminated with nitrate, it is probably too late and too difficult to correct the problem within a short period of time. Corrective measures may not be effective, as shown by current high nitrate concentrations despite previous efforts to resolve the problem. Therefore, we must try to keep nitrate levels within acceptable limits. If action is not taken now, future generations will pay the price of current bad practice in agriculture. International water quality guidelines permit a maximum of 50 mg nitrates/l for adults and of 25 mg/l for infants and pregnant women. The intake of nitrates in drinking water by humans is currently one of the major environmental problems associated with agricultural practice. Nitrate is itself inert but concern arises due to its possible conversion into nitrite, which is highly toxic. We analyzed the nitrate content of water samples from 15 private wells currently used for human consumption and agricultural in an effort to deal with the nitrate pollution of groundwater supplies in the Akkar Plain. We found that 14 of the 15 wells had a nitrate concentration above 50 mg/l, with a maximum of 163 mg/l. In addition, salt water was found to have contaminated groundwater supplies in some of the villages along the coastline in the north. Our results indicate that the groundwater is seriously contaminated with nitrates, to the extent that it does not meet international drinking water standards. These high nitrate levels may have adverse effects and cause disease. The toxic effects of nitrate contamination are most severe in individuals with weak immune systems, such as the elderly and children. We are currently developing solutions and preventive measures for this extremely worrying situation, based on these data.
Halwani
J
J
Université libanaise, Faculté de santé publique, BP 246, Tripoli, Liban.
Baroudi
B O
BO
Wartel
M
M
D000328:Adult; D000368:Aged; D002648:Child; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007861:Lebanon; D008297:Male; D008452:Maximum Allowable Concentration; D009566:Nitrates / Q000032:analysis*; D011247:Pregnancy; D013053:Spectrophotometry; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply / Q000032:analysis* / Q000592:standards
D009566:Nitrates; D014874:Water Pollutants, Chemical