Laser Fluorimetry Research Articles

Distribution of naturally occurring uranium and other heavy toxic elements in selected spring water samples of Pithoragarh District, Uttarakhand, India

The main purpose of this study was to investigate the seasonal variation of the uranium (U) concentration level in natural drinking water. Laser fluorimetry technique has been used for the microanalysis of uranium concentration in water samples collected from different natural sources like springs and subterranean springs of various depths. A total of 23 drinking water samples were collected based on their consumption for drinking purposes from the different areas of Pithoragarh district. Seventeen physico- chemical parameters, six heavy metals and uranium were estimated in the samples. The results showed that the average value of TDS was observed 204.65 mg/L during pre- monsoon season and 213.82 mg/L during post- monsoon season, the uranium concentration in drinking water samples varied from 0.10–9.90 µg L−1 in pre-monsoon and 0.10–8.32 µg L−1 in post-monsoon seasons. The study revealed that none of the samples had exceeded the guideline values prescribed for concentration of uranium in drinking water by World Health Organization (30 µg L−1) and sources can be considered safe with respect to the level of uranium concentration.

Comparison of four analytical techniques for determining uranium in different rock samples

Four different analytical techniques were compared for their performance in direct determination of uranium in seven rock samples. These methods include: ion chromatography, laser fluorimetry, UV–Vis spectrophotometry and gamma spectrometry. The samples under study were six ore samples beside an international reference sample (GBWO4115). The results obtained from the comparison study reported a method accuracy of 98%, 90%, 65% and 86% for ion chromatography, laser fluorimetry, UV–Vis spectrophotometry and gamma spectrometry techniques respectively. Also, on the converse of the other three techniques, ion chromatography technique using DX-500 ion chromatograph achieves superior agreement with the certified sample with only 2% bias.

Health-Related Analysis of Uranium in Fazilka District, Punjab, India

Laser fluorimetry technique has been used to estimate uranium concentration in groundwater samples collected from 20 villages of Fazilka district, Punjab, India. The uranium concentration was found to vary from 4.32 to 83.99 μg l –1 at different locations with mean concentration of 26.51 μg l –1 . Also, 24% of the drinking water samples exceeded the safe limits set by WHO, while 9% was above the limit set by AERB. Certain health risk factors like annual effective dose, excess cancer risk and lifetime average daily dose were also evaluated. The study also included uranium estimation in soil samples collected from the same villages using wavelength dispersive X-ray fluorescence technique. All the values were found to be well within the safe limits. Topography of the region seems to be the most likely reason for higher uranium concentration at some locations.

Uranium content in groundwater by laser fluorimetry; method validation and dose assessment

In this study, the total uranium concentration was determined in groundwater samples used for irrigation and/or drinking purposes and collected from private wells in Al Sharqiya region, Saudi Arabia. The uranium concentrations were measured by laser fluorimetry preceded by radiochemical treatment to eliminate the quenching effect due to the high total dissolved solids content in the groundwater samples. For method validation, some of the measured samples were analyzed for uranium isotopic activities and measured by alpha spectrometry. The results of the uranium concentrations obtained by laser fluorimetry and alpha spectrometry were in good agreement. The uranium concentrations in all the samples were below the World Health Organization (WHO) recommended limit of 30 μg L−1. Two different approaches were followed to assess the annual effective dose from the ingestion of uranium in the analyzed groundwater samples. The annual effective doses determined by the two approaches were found to be in agreement, and varied from 2.9 to 10.2 μSv y−1, with a mean value of 6.1 μSv y−1, which is far below the WHO recommended level of 100 μSv/y. The modified laser fluorimetric procedure was found to be a good tool compared with other techniques for direct measurement of uranium concentrations in high total dissolved solids groundwater samples at low levels.

Comments on Uranium Content in Groundwater by Laser Fluorimetry: Method Validation and Dose Assessment

Comments on Uranium Content in Groundwater by Laser Fluorimetry: Method Validation and Dose Assessment

Measurement of uranium and radon concentration in drinking water samples and assessment of ingestion dose to local population in Jalandhar district of Punjab, India

A study was conducted to assess the concentration of uranium and dissolved radon in drinking water samples collected from Jalandhar district of Punjab, India. The samples were analysed for dissolved radon using scintillation cell method. Laser fluorimetry was used for measurement of uranium concentration. Correlation analysis of radon and uranium concentrations and salinity and total dissolved solids with uranium was carried out. The uranium concentration in water samples varied from a minimum value of 1.53 ± 0.06 mg m−3 to 50.2 ± 0.08 mg m−3 with a geometric mean value of 14.85 mg m−3. The radon concentration in water varied from a minimum value of 0.34 ± 0.07 kBq m−3 to a maximum value of 3.84 ± 0.48 kBq m−3 with a geometric mean value of 1.46 kBq m−3. Ingestion dose to local population, due to radon and uranium in drinking water, for different age categories, was computed and results are being reported in this paper.

A study on uranium and radon levels in drinking water sources of a mineralized zone of Himachal Pradesh, India

The uranium (238U) and radon (222Rn) concentration measurements have been carried out in drinking water samples collected from Hamirpur and Kangra districts of Himachal Pradesh and adjoining areas of Jammu and Kashmir, India by using Laser Fluorimetry technique and Scintillation based radon monitor respectively. The 238U and 222Rn concentrations in these samples are found in the range of 0.26 ± 0.1 to 29.5 ± 2.5 µg l−1 and 0.86 ± 0.12 to 7.62 ± 0.64 Bq l−1 respectively. The measured values of 238U and 222Rn concentration are within the safe limits as recommended by WHO and USEPA. The annual effective doses are also observed to be below the prescribed dose limit of 100 µSv year−1 recommended by WHO.

Uranium and other heavy toxic elements distribution in the drinking water samples of SW-Punjab, India

In the present investigations, Laser Fluorimetry technique has been used for the microanalysis of uranium content in drinking water samples collected from different sources like the hand pumps, tube wells of various depths from wide range of locations in the four districts of SW-Punjab, India. The purpose of this study was to investigate the uranium concentration levels of ground water being used for drinking purposes and to determine its health effects, if any, to the local population of this region. Corresponding radiological and chemical risks have also been calculated for the uranium concentrations in ground water samples. Some other heavy elements have also been analysed using the Atomic Absorption Spectrometry. In this region, uranium concentration in 498 drinking water samples has been found to vary between 0.5–579 μgl−1with an average of 73.5 μgl−1. Data analysis revealed that 338 of 498 samples had uranium concentration higher than recommended safe limit of 30 μgl−1 (WHO, 2011) while 216 samples exceeded the threshold of 60 μgl−1 recommended by AERB, DAE, India, 2004.

Technology to Harvest Uranium from Seawater and Its Estimation by Laser Fluorimetry

Process technology for extraction of uranium from seawater has been initiated in India on bench scale field trials and for this purpose special adsorbents have been synthesised by radiation grafting technique. These adsorbents are in the form of leaflets that provide efficient contact patterns with water body in the sea. However, it was observed that during the extraction of uranium from seawater/brine, a few transition elements like vanadium also got extracted by the adsorbents. The product elute solutions were then stored in large glass-lined mild steel tanks, which lead to the extraction of iron from the tanks into the solutions. The main challenge was to separate uranium from these transition elements and then estimate its concentration by laser fluorimetry (LF). This paper reports the radiochemical separation procedure standardised for determining the concentrations of uranium metal ions from lean solutions of seawater/brine and its estimation by LF.

Concentrations of uranium in drinking water and cumulative, age-dependent radiation doses in four districts of Uttar Pradesh, India

The present work deals with the determination of uranium concentrations in drinking and ground water samples by laser fluorimetry and calculation of cumulative, age-dependent radiation doses to humans. The concentrations were found to be between 0.20 ± 0.03 and 64.0 ± 3.6 μg L−1, with an average of 11.1 ± 1.5 μg L−1, well within the drinking water limit of regulatory bodies. The concentrations of uranium increase with depth of water samples collection. The estimated annual ingestion dose due to the intake of uranium through drinking water for all age groups varied between 0.2 and 137 μSv a−1, with an average of 17.3 μSv a−1. The mean annual ingestion dose is 5% of the global average ingestion dose, for infants, marginally higher than for other age group. Most effective dose values were less than 20 μSv a−1.

Distribution of uranium concentration in groundwater samples from the Peddagattu/Nambapur and Seripally regions using laser fluorimetry

Uranium is a naturally occurring element, which is widespread in nature. It is found in low levels within all rocks, soils and water. Peddagattu and Seripally areas of Nalgonda district, Andhra Pradesh, India were known as a rich uranium mineralised zone. Atomic mineral division and Baba Atomic Research Center proposed a uranium mine in this area. This study was carried out to know the distribution of uranium concentration in the groundwater samples by using laser fluorimetry. The observation reveals that the uranium concentration in the groundwater of this region ranges from 0.6 to 521.15 ppb. About 43 % of the groundwater samples had the uranium concentration above the standards set by United States Environmental Protection Agency (30 ppb).

Determination of selected natural radionuclide concentrations in southwestern Caspian groundwater using liquid scintillation counting

Twenty-seven spring water samples from southwestern shore of the Caspian Sea were analysed for their contents of gross alpha and beta, ²²²Rn, ²²⁶Ra and total uranium using a liquid scintillation counter (LSC). Other methods such as the Environmental Protection Agency (EPA) method 900 for gross alpha/beta measurement, radon emanation for ²²⁶Ra determination and laser fluorimetry for total uranium content were applied to make a comparison with the LSC technique. The levels of measured ²²²Rn and ²²⁶Ra range from 0.5 to 54 Bq l⁻¹ and from 14 to 297 mBq l⁻¹, respectively. The levels of gross alpha and beta are from 16 mBq l⁻¹ to 1.0 Bq l⁻¹ and from 22 to 630 mBq l⁻¹, respectively. The total uranium contents are from 3 to 66 mBq l⁻¹. It has been shown that the simple liquid scintillation counting technique could be applied conveniently for such studies where analysis of numerous samples is concerned.

Letter to Editor : Query related to publication titled “A comparative analysis of uranium in potable waters using laser fluorimetry and ICPMS techniques” by Shenoy et al. 294:413–417 (2012), doi: 10.1007/s10967-012-1705-2

Dear Editor, I have read the above cited paper very carefully. Undersigned has been involved in the analysis of geological materials and hydro-geochemical reconnaissance surveys attached with mobile geochemical laboratories in different parts of India for uranium exploration activities of Atomic Minerals Directorate for Exploration and Research. I have also contributed on uranium determination in diverse matrices vide my publications: Accred. Qual. Assur. 17 (2012) 75–84; Talanta 77 (2008)9–20; Explor. Res. At. Miner. 17 (2007)145–149; Talanta 62 (2004) 343–349; J. Radioanal. & Nucl. Chem., 253 (2002) 135–142; Anal. Chim. Acta 434 (2001) 201–208; Mikrochim. Acta 137 (2001) 127–134; Fresenius J. Anal. Chem., 370 (2001) 377–383, Analyst, 125(2000) 1221–1226. Based on my experiences gained so far, I would like to share some of my observations as follows: There are two essential parameters for the reliability of chemical analysis for naturally occurring water samples:

Author’s response to “query related to publication titled ‘A comparative analysis of uranium in potable waters using laser fluorimetry and ICPMS techniques’ by Niyoti S. Shenoy, Ananya Verma, S. A. Kumar, S. Pandey, Sangita D. Kumar, A. V. R. Reddy, published in J Radioanal Nucl Chem (2012) 294:413–417, DOI 10.1007/s10967-012-1705-2”

Author’s response to “query related to publication titled ‘A comparative analysis of uranium in potable waters using laser fluorimetry and ICPMS techniques’ by Niyoti S. Shenoy, Ananya Verma, S. A. Kumar, S. Pandey, Sangita D. Kumar, A. V. R. Reddy, published in J Radioanal Nucl Chem (2012) 294:413–417, DOI 10.1007/s10967-012-1705-2”

Laser flourimetric analysis of uranium in water from Vishakhapatnam and estimation of health risk

Uranium is a naturally occurring radioactive element that is both radiologically and chemically toxic. The presence of uranium in the aquatic environment is due to the leaching from natural deposits, release in mill tailings, the combustion of coal and other fuels, and the use of phosphate fertilizers that contain uranium. Intake of uranium through air and water is normally low, but in circumstances in which uranium is present in a drinking water source, the majority of intake can be through drinking water route. The uranium concentrations in ground water samples from Vishakhapatnam, India were estimated using laser fluorimetric technique and were observed to range from 0.6 to 12.3 ppb. The laser fluorimetry technique was found to be an excellent tool for direct measurement of uranium concentration in water samples at ultra-trace levels. The annual effective dose, cumulative dose for 70 years and the lifetime excess cancer risk from drinking of this water were calculated. The risks were low averaging only 10.6 × 10 -6 as none of the samples were observed to exceed the WHO recommended uranium concentration limit of 30 ppb.

Investigation of OCP-triggered dissipation of excitation energy in PSI/PSII-less Synechocystis sp. PCC 6803 mutant using non-linear laser fluorimetry

In order to prevent photodestruction by high light, photosynthetic organisms have evolved a number of mechanisms, known as non-photochemical quenching (NPQ), that deactivate the excited states of light harvesting pigments. Here we investigate the NPQ mechanism in the cyanobacterium Synechocystis sp. PCC 6803 mutant deficient in both photosystems. Using non-linear laser fluorimetry, we have determined molecular photophysical characteristics of phycocyanin and spectrally distinct forms of allophycocyanin for the cells in non-quenched and quenched states. Our analysis of non-linear fluorescence characteristics revealed that NPQ activation leads to an ~2-fold decrease in the relaxation times of both allophycocyanin fluorescence components, F660 and F680, and a 5-fold decrease in the effective excitation cross-section of F680, suggesting an emergence of a pathway of energy dissipation for both types of allophycocyanin. In contrast, NPQ does not affect the rates of singlet–singlet exciton annihilation. This indicates that, upon NPQ activation, the excess excitation energy is transferred from allophycocyanins to quencher molecules (presumably 3′hydroxyechinenone in the orange carotenoid protein), rather than being dissipated due to conformational changes of chromophores within the phycobilisome core. Kinetic measurements of fluorescence quenching in the Synechocystis mutant revealed the presence of several stages in NPQ development, as previously observed in the wild type. However, the lack of photosystems in the mutant enhanced the magnitude of NPQ as compared to the wild type, and allowed us to better characterize this process. Our results suggest a more complex kinetics of the NPQ process, thus clarifying a multistep model for the formation of the quenching center.

Estimation of uranium in bioassay samples of occupational workers by laser fluorimetry

A newly established uranium processing facility has been commissioned at BARC, Trombay. Monitoring of occupational workers is essential to assess intake of uranium in this facility. A group of 21 workers was selected for bioassay monitoring to assess the existing urinary excretion levels of uranium before the commencement of actual work. Bioassay samples collected from these workers were analyzed by ion-exchange technique followed by laser fluorimetry. Standard addition method was followed for estimation of uranium concentration in the samples. The minimum detectable activity by this technique is about 0.2 ng. The range of uranium observed in these samples varies from 19 to 132 ng/L. Few of these samples were also analyzed by fission track analysis technique and the results were found to be comparable to those obtained by laser fluorimetry. The urinary excretion rate observed for the individual can be regarded as a ‘personal baseline’ and will be treated as the existing level of uranium in urine for these workers at the facility.

A comparative analysis of uranium in potable waters using laser fluorimetry and ICPMS techniques

The main objective of this work is the accurate measurement of uranium in the potable water sources of Muktsar district of Punjab, India. In the present work, a laser fluorimetry technique was used for the analysis of uranium. Inductively coupled plasma mass spectrometry (ICPMS) technique was also applied to verify and compare the uranium content analyzed using laser technique. About 16 samples from waterworks, bore wells, and hand pumps that supply the drinking water to local population were collected for this purpose. An indigenous laser fluorimeter supplied by RRCAT, Indore was employed for the analysis. Uranium concentrations obtained were in the range from 0 to 10 μg L−1 in ten samples, 11–30 μg L−1 in three samples, and more than 100 μg L−1 in three samples namely Channu ground water, Warning Khera pump, and Killanwale village hand pump. The USEPA guideline value for uranium in safe drinking water is 30 μg L−1. Also, a data comparison with similar studies carried out in other countries is presented.

Studying photoprotective processes in the green alga Chlorella pyrenoidosa using nonlinear laser fluorimetry

We use an advanced fluorescence method of Nonlinear Laser Fluorimetry in combination with Fluorescence Induction and Relaxation technique to study the influence of excess-light conditions on the physiological state of the green alga Chlorella pyrenoidosa. We demonstrate that zeaxanthin-dependent non-photochemical quenching leads to a significant increase in the rate constant of singlet-singlet annihilation of chlorophyll a excited state, which suggests profound conformational changes in the light-harvesting complexes of photosystem II.

Application of fission track technique for estimation of uranium concentration in drinking waters of Punjab

Drinking water samples were collected from four different districts, namely Bhatinda, Mansa, Faridkot and Firozpur, of Punjab for ascertaining the U(nat.) concentrations. All samples were preserved, processed and analyzed by laser fluorimetry (LF). To ensure accuracy of the data obtained by LF, few samples (10 nos) from each district were analyzed by alpha spectrometry as well as by fission track analysis (FTA) technique. For FTA technique few μl of water sample was transferred to polythene tube, lexan detector was immersed in it and the other end of the tube was also heat-sealed. Two samples and one uranium standard were irradiated in DHRUVA reactor. Irradiated detectors were chemically etched and tracks counted using an optical microscope. Uranium concentrations in samples ranged from 3.2 to 60.5 ppb and were comparable with those observed by LF.