当前世界环境

Introduction

水宝llution due to heavy metal particularly mercury resulting from various anthropogenic sources are causing serious ecological problems in many part of the world. Poor environmental management with respect to use of mercury in the society to meet our day to day requirement may aggravate the adverse effect on the various component of environment. This may leads to the transformation mercury from one compartment of environment to another, including the biota with detrimental effects. Literature shows the sufficient accumulation of the mercury in biota through food chain transfer, there is also an increasing toxicological risk for man.

A famous episode of Minanata disease occurred in Japan in fifties due to consumption of fish contaminated by methyl mercury.⁵Mercury in natural water can exists in truly, colloidal and suspended forms.

The mercury is used in various medical devices particularly temperature and blood pressure measuring gadgets. The following are the major equipment in which mercury is used.

• Clinical and normal thermometer
• Sphygmomanometer
• Dilators
• Dental amalgam
• Lab chemicals such as zenkers solution, histological fixatives

In normal case leakage or spillage of mercury from thermometer or any devices, clean up without use of protective gears and proper disposal system. This not only exposes the health workers who are handling mercury spills but also the community at large in long term. The waste spilled mercury is thrown in community dustbin, flushed down the sewer or incinerated. When incinerated, it may volatilize and become airborne or eventually settles in water bodies from where through bioaccumulation and bio magnification route may reach to humans kind. The accumulation of mercury in muscle tissue may jeopardize cell division, binds with DNA interfering with replication of chromosomes and protein synthesis.

Material and Methods

The Bhopal city, capital of Madhya Pradesh state is situated above 500 m. above MSL between 23.16 N latitude and 77.36 E longitude having population figure just over 1.8 million, has been selected for the study. During the study both kind of drains, which cover private and government hospitals were covered. In Bhopal more then 250 health care facilities are operating at various part of the city.

Five monitoring location on various hospital drains were identified to assess the contribution of mercury to public sewer. The sampling was carried out on quarterly basis for two year continuously during January 2005 to October 2006. Sampling schedule were fixed in the first week of every quarter month of year in the morning hour between 10.00 am to 1.00pm.The details of the sampling location are as given in Table -1.

The standard methods as prescribed in APHA adopted for analysis of wastewater samples during study.^1,4The primary conditioning of the samples were carried at the site followed by analysis in the laboratory using Mercury analyzer, Electronic Corporation model -5840.^2,6The instrument work on cold vapor atomic absorption spectroscopy technique at 353nm.

Take a suitable aliquot of the sample, blank and standards in a reaction vassal. Add the required amount of 10% HNO₃to maintain a vol. of 10 ml. Add 2 ml of 20% SnCl₂in sample and placed the stopper immediately, switch on the magnetic stirrer. The cold vapor of the Hg is produced. Measure the absorbance of the sample and extra polote the Hg concentration from analytical calibration graph. Plot the analytical calibration graph of absorbance vs concentration of Hg in micro gm/l.

mg value by graph x dilution
Calculation :Hg mg/l :^{_____________________________}
Vol. of sample

Table -1

结果与讨论

研究下水道中的汞浓度是总统ented at table. The results, shows that concentration of mercury well within the discharge limits set by CPCB³except at two drains i.e. near Priyadershni market and Sultania hospital. The highest concentration i.e. 0.02 mg/l were recorded at these locations. This higher concentration in the aquatic environment may pose serious threats to aquatic biota, which may ultimately reflect to human health. Concentration of mercury at other location ranges between BDL to 0.005 mg/l. In the month of July 2005 and 2006 mercury value found BDL due to dilution by rainwater.

Table - 1: Mercury Concentration in major public sewers near hospitals

^{All the values are in mg/lBDL-Below detectable limit}

Conclusion

Variation in the concentration of mercury with relation to time and locations were observed in the study. In the second year of study i.e. 2006, the concentration of mercury reduced remarkably. Major causes for the reduction of mercury concentration may be due to replacement of the traditional mercury based instrument by digital instrument as well as strict implementation of BMW ( M & H) rule by the hospital authority.

Acknowledgements

The authors are thankful to In charge Zonal Officer ,CPCB Bhopal for the facilities provided to carry out this study.

References

1. APHA, American Public Health Association, standard methods for the examination of water and waste water, 20th edition New York
2. Laboratory analysis technique /17/2004- 2005 CPCB
3. Pollution control acts rules and notifications issued there under series PCLS/02 (2006).
4. Sawyer N.C.McCarty P L and Parkin, GF “Chemistry for Environmental engineering”.
5. Pariwesh newsletter of CPCB (2005).
6. Manual of mercury analyzer ECL, Hydrabad.