Effects of season and daily changes in nitrate N03- contaminant levels of lettuce

Ahmad Z., . and Mohammadreza M., . (2007) Effects of season and daily changes in nitrate N03- contaminant levels of lettuce. [Proceedings Paper]

Vegetables contain higher concentrations of nitrate than those of other foods and provide the major contribution to dietry intake of nitrates. Nitrates NO3- are present naturally or may be present as a result of applying nitrogen N fertilizers on crops or from its use as a preservative. There have been health concerns about the presence of NO3- in food as it can be metabolized to potentially carcinogenic N-nitroso compounds. The main sources of NO3- and NO2- in diets are vegetables and meats. According to the U.S. Department of Agriculture the average adult ingests about 25 mg of NO3- - N per day in foods. Varamin is the most important county for agriculture in Tehran province. Many scientists have studied factors affecting NO3- concentrations in plants. However none have determined nitrate concentrations in harvested plants. In this study some of the fields in the Varamin area that have used the same type of N fertilization were chosen at random. Concentrations of NO3- in lettuce were determined by sampling during different seasons and times of the day 3 replications in each fields. The NO3- contaminant levels of lettuce compared with general standards FAO EC WHO standards using the t-test. For this study plants were sampled near the harvest and NO3- concentrations in the plants leaves were measured at 4:00-8:00am and also at 14:00-16:00pm on the same day in the spring and the fall. The standards EC andamp; WHO permitted maximum NO3- concentration is 3 000 - 3 500 mg kg-1. We found that NO3- concentrations in lettuce in the morning were much lower than those in lettuce harvested the afternoon. Results showed that the NO3- concentrations in lettuce leaves ranged from 4 287 mg kg-1 to 13 304 mg kg-1. We found significant differences P less than 0.01 between measurements and all of our samples would be considered to have some degree of NO3- pollution in comparison with the EC standards.

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Abstract

Vegetables contain higher concentrations of nitrate than those of other foods and provide the major contribution to dietry intake of nitrates. Nitrates NO3- are present naturally or may be present as a result of applying nitrogen N fertilizers on crops or from its use as a preservative. There have been health concerns about the presence of NO3- in food as it can be metabolized to potentially carcinogenic N-nitroso compounds. The main sources of NO3- and NO2- in diets are vegetables and meats. According to the U.S. Department of Agriculture the average adult ingests about 25 mg of NO3- - N per day in foods. Varamin is the most important county for agriculture in Tehran province. Many scientists have studied factors affecting NO3- concentrations in plants. However none have determined nitrate concentrations in harvested plants. In this study some of the fields in the Varamin area that have used the same type of N fertilization were chosen at random. Concentrations of NO3- in lettuce were determined by sampling during different seasons and times of the day 3 replications in each fields. The NO3- contaminant levels of lettuce compared with general standards FAO EC WHO standards using the t-test. For this study plants were sampled near the harvest and NO3- concentrations in the plants leaves were measured at 4:00-8:00am and also at 14:00-16:00pm on the same day in the spring and the fall. The standards EC andamp; WHO permitted maximum NO3- concentration is 3 000 - 3 500 mg kg-1. We found that NO3- concentrations in lettuce in the morning were much lower than those in lettuce harvested the afternoon. Results showed that the NO3- concentrations in lettuce leaves ranged from 4 287 mg kg-1 to 13 304 mg kg-1. We found significant differences P less than 0.01 between measurements and all of our samples would be considered to have some degree of NO3- pollution in comparison with the EC standards.

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Item Type:	Proceedings Paper
Additional Information:	Available at Perpustakaan Sultan Abdul Samad Universiti Putra Malaysia 43400 UPM Serdang Selangor Malaysia. mal S590.2 S683 2007 Call Number
AGROVOC Term:	LETTUCES
AGROVOC Term:	NITRATES
AGROVOC Term:	POLLUTION
AGROVOC Term:	SOIL POLLUTION
AGROVOC Term:	POLLUTANTS
AGROVOC Term:	SEASONS
AGROVOC Term:	IRAN ISLAMIC REPUBLIC
Geographical Term:	MALAYSIA
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 05:13
URI:	http://webagris.upm.edu.my/id/eprint/10918

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