Agricultural Research Management Information System

Home
Research Summary
Search
About Us
- ARMIS
- Brochure
Contact Us
Report
User Request
Data Input
Help
- Operation Manual
  - PDF
  - Video
- Program Area & Commodity
We have reached 37600 number of research entries at this moment.

- Logout

Research Detail

Home
Research
Detail

Semiquantitative Determination of Chromium Content of River Bed Soil of Buriganga River at Different Locations

M. E. SADAT
Department of Physics, University of Dhaka, Dhaka-1000, Bangladesh

A. F. M. Y. HAIDER*
Department of Physics, University of Dhaka, Dhaka-1000, Bangladesh

K. M. ABEDIN
Department of Physics, University of Dhaka, Dhaka-1000, Bangladesh

M. WAHADOSZAMEN
Department of Physics, University of Dhaka, Dhaka-1000, Bangladesh

A. I. TALUKDER
Department of Physics, University of Dhaka, Dhaka-1000, Bangladesh

Abstract/ Executive Summary:

Using the technique of Laser Induced Breakdown Spectroscopy, the chromium content of river bed sediment of the Buriganga River is determined at various locations. Hazardous element, chromium is found in addition to other elements such as calcium, magnesium, titanium, sodium etc. The source of this chromium is most likely to be the effluent discharge from the tanneries located nearby. Semi quantitative analyses showed the relative abundances of Cr, Mg, and Ca in the river bed sediment at Kamrangir Char and Shoari Ghat locations are in the ratios of 1:9:23 and 1:11:17, respectively.

Keywords: Chromium content; River bed soil; Buriganga river

Location: Buriganga River, Dhaka

Start Date:

End Date:

Program Area: Risk Management in Agriculture

Commodity: Heavy metal

Objectives:

To determine the concentration of chromium content of river bed soil of Buriganga River at different locations

Methodology:

The excitation laser is a Q-switched Nd:YAG laser system (Spectra-Physics LAB-170-10) which has output at fundamental wavelength of 1064 nm with pulse duration of 8 ns, repetition rate of 10 Hz and pulse energy of 850 mJ. The laser is also equipped with harmonic generators capable of generating the second and third harmonics of the fundamental at 532 nm and 355 nm by means of KDP crystals and producing energies of 450 mJ and 220 mJ per pulse, respectively. In the present experiment the second harmonic at 532 nm was used. Intense, transient plasma is produced by focusing the laser beam on the sample by a convex lens of 100 mm focal length. The plasma is generated at the repetition rate of the laser, i.e. at 10 times per second. The light emitted by the plasma was collected by a short focal length lens and focused onto a 3 m long multimode optical fiber bundle. The light is transmitted through the fiber bundle to its other end which is placed at the entrance slit of a 750 mm focal length computerized Czerny-Turner spectrograph (Acton Model SP- 2758). The spectrograph is equipped with two ruled gratings; 300 grooves/mm and 1200 grooves/mm, which are interchangeable under computer control, providing low resolution and high resolution spectra, respectively. The output end of the spectrograph is placed in conjunction with a scientific-grade CCD camera (Roper Scientific PIXIS 100B). The CCD camera has 1340 × 100 pixels and is cooled to – 68 C by a four-stage Peltier cooler to reduce noise. The spectral data captured by the CCD camera is transferred to the personal computer by means of high speed USB connection cable. All the function of the PIXIS camera and the Acton spectrograph can be fully controlled by WinSpec software provided by the manufacturer. The CCD camera was usually set to spectroscopy mode. In this mode, all the 100 pixels in the vertical direction are summed (binned) in hardware before digitization is performed, resulting in an improved signal-to-noise ratio. The camera can support data acquisition rates (frame rates) as high as 500 Hz in this mode. If 300 grooves/mm grating is used, a spectrum of about 120 nm width can be captured without moving the grating, and for the 1200 grooves/mm grating, it is only 30 nm. However, this width is insufficient to cover all the wavelengths of the emission spectrum from the sample. Hence, to cover a wider region, the grating was stepped under computer control, and data acquisition was performed at each grating position. Finally, the collected spectra were electronically glued. All this functions were performed by WinSpec software. To find out all the elements within the sample we tried to acquire spectra covering as wide region as possible. But the higher limit of wavelength sensitivity of our detection system is determined by the drop-off of CCD sensitivity in the IR, limiting the useful operation to less than about 900 nm. The lower spectral limit is determined by loss of diffraction efficiency of the grating (blazed at 300 nm) and the absorption of the collection lens and the optical fiber in the UV. Overall, the lower limit of our system is about 200 nm. The laser was operated at 10 Hz and the camera was allowed to operate in the free running mode without any synchronization of the laser (non-gated mode). Integration times of up to 10 sec were used to acquire spectra, and hence, an emission spectrum was accumulated from an average of up to 100 shots. This averaging process eliminates any short-term instability of the laser.

Source of Information: Journal of Bangladesh Academy of Sciences, Vol. 34, No. 2, 123-131, 2010

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

In conclusion, it is stated that using the technique of LIBS, chromium can be detected in river sediment and it can be semi-quantitatively determined. The technique thus opens up the possibility of detecting other toxic elements discharged in the environment as a result of the activities of various industries, such as paint industries, electroplating industries, foundry and workshops etc.

Knowledge Management: Journal