الفهرس 
CONTENTSOnly 14 pages are availabe for public view
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Abstract
The increased nitrate levels in groundwater and consequently surface water is a major problem, caused by N-fertilizers that are used in most areas with intensive agriculture like Dakahlia province, Egypt. Therefore, a study has been carried out to assess quality of water samples collected from private wells existing within agricultural fields that are defined as ”field groundwater” and others from wells near or between houses and far from fields that are named as ”domestic groundwater”, as well as tap water with regard to nitrate concentration and other chemical constituents (salinity, alkalinity, chloride, sulfate, calcium, magnesium, sodium and potassium levels, as well as pH-value) in a number of villages (Kom El-Derbi, El-Baramon, Badaway, Meet Nabet, Bosat El-Nasara, Kafr El-Sherbini, Monshaat Mansour, Nawasa El-Bahr, Temy El-Amdid, Ezbat Shaban and Kom El-Nour) located at Dakahlia province. Water samples were collected from each village monthly during winter (December, January, February) and summer (June, July and August) 2004. A)Water analysis: A total of 132 groundwater samples, as well as 66 tap water samples were collected and analyzed during the whole study period.B) Physiological Study: Commonly observed effects in nitrate-exposed animals include: C) Histological investigation: The stained hematoxylin–eosin thyroid sections of all investigated animals with both medium and high nitrate doses showed adverse effects, especially with the young age groups that were represented by: -Flatness of follicular epithelium and appearance of nuclear pyknosis. -Reduction or absence of colloid in follicles. -Appearance of non-functional microfollicles. -Appearance of hyperplasia between follicles.