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Levels of Reactive Nitrogen in Surface and Ground Water Samples Obtained from Different Parts of Bangladesh

M. ANOWAR
Department of Microbiology, Jahangirnagar University, Savar, Bangladesh

K. PARVEZ
Department of Microbiology, Jahangirnagar University, Savar, Bangladesh

MAHFUZA MARZAN,
Department of Microbiology, Jahangirnagar University, Savar, Bangladesh

SYEDA MORIAM LIZA AND
Department of Microbiology, Jahangirnagar University, Savar, Bangladesh

ZIA UDDIN AHMED*
Department of Microbiology, Jahangirnagar University, Savar, Bangladesh

Abstract/ Executive Summary:

A total of 114 water samples collected from different parts of Bangladesh were analyzed for the level of reactive nitrogen species NO₃ and NH3. Nitrate was determined in 20 surface water, 28 motorized deep tube well and 66 hand operated tube well samples. Ammonia was determined in 18 surface water, 14 deep tube well and 49 hand operated tube well samples. These sites were randomly selected. Nitrate levels were found to be generally low (below 3 mg/l) in 112 of the 114 samples tested, which is much below permissible level of 10 mg/l of drinking water in Bangladesh. Ammonia concentration was, however, found to be about 4 mg/l in majority of the samples tested which is higher than maximum permissible limit of 0.5 mg/l in drinking water. Possible reasons for low level of nitrate and relatively high level of ammonia in surface and ground water samples in Bangladesh is discussed

Keywords: Reactive nitrogen; Nitrate and ammonia; Surface and ground water; Bangladesh

Location: Bangladesh (mainly central Bangladesh and adjoining areas on the north and south)

Start Date:

End Date:

Program Area: Resource Development and Management

Commodity: Fertilizer

Objectives:

To undertake an exploratory study on the levels of NO₃ and NH₃ in samples of surface and ground water over a region of the country.

Methodology:

A total of 114 water samples were collected in sterile plastic bottles (200 - 300 ml) from different parts of Bangladesh (mainly central Bangladesh and adjoining areas on the north and south). These samples included water from deep tube wells, hand operated shallow tube wells and closed inland water bodies such as ponds and lakes (Beels). Samples were analyzed within 24 hrs after collection generally without the samples being refrigerated. It was difficult to ascertain the depth of the large number of tube wells used, but a rough guess can be made. Hand operated tube wells in Bangladesh usually occur at depth of around 45 meters and deep tube wells about 150 meters. Several parameters that are routinely analyzed in water sample analysis such as pH, temperature, electrical conductivity (EC), total suspended solids (TSS), and biological oxygen demand (BoD) were determined for the samples. These have not been presented as they do not have significant direct relevance to the central focus of the study, which is providing an indication of NO3 and NH3 levels at random sites in a certain region of the country obviously avoiding sites dedicated to high level specific human activity. For general interest, however, the ranges found were: pH 5.2 - 9.2, temperature 27.5 - 29.5, EC 0.66 - 10.98, TSS 1600 - 6800 mg/l, BoD 0.08 - 1.3 mg/l. It should be mentioned that extreme values were found only in a few cases. Nitrate concentration in most of the water samples was determined by spectrophotometric method (APHA 1998) by measuring UV absorbance at 205 nm using a UV Specord 205 Analytic Jena spectrophotometer with quartz cells of 1 cm light path. A standard curve for nitrate concentration was prepared by dissolving 0.0722 g KNO₃ in 100 ml nanopure water to make a stock solution containing 100 µg/ml NO₃-N. Dilutions of this solution were made to contain various concentrations of nitrate and absorption was measured at 205 nm. Absorption increased in a linear manner for up to 6 µg/ml NO₃ and this region of the curve was used to determine nitrate concentration of the experimental water samples. In some of the water samples nitrate determination was also carried out by steam distillation method (Bremner 1965). Nitrate levels in samples obtained from different sources were generally similar in both the methods used in the study. As such, the authors have pooled together the nitrate values obtained by these two methods and results presented in one Table. Ammonia concentration was determined by steam distillation method (Bremner 1965). Per cent recovery in steam distillation method was not experimentally determined but assume to be over 99%. In the absence of correction for possible loss during processing the values may be regarded as representing the lower limits.

Source of Information: Journal of Bangladesh Academy of Sciences, Vol. 38, No. 1, 75-82, 2014

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Preliminary observations (results not shown) suggest that surface water in Bangladesh which is generally of high trophic level can potentially carry high load of nitrogen metabolizing bacteria including bacteria that can grow in vitro at high levels of exogenous nitrate (nitrate tolerant bacteria). Contributions of associated bacterial population in maintaining reactive nitrogen balance in water and soil may be a subject of both academic interest and of potential practical value.

Knowledge Management: Journal