ABSTRACTS
1. Impact of Awareness of Arsenic on Health and
Environment among the Rural
People: A Case Study on the Villages of North 24-Parganas.
Pralay O’ Basu, R. Chakraborty and Nirupama Bhattacharya.
2. Arsenic Contamination of Drinking Water in
Rural Areas Of India and Its Bearing on Indian Economy.
Kaustav Bhattadharyya.
3. Geochemistry of Arsenic in Ganga
Sediment: A case Study in West Bengal, India.
S. Chakraborty, B. Nath, J. Jana, P. Mukherjee and
D. Chatterjee.
4. Geochemistry of Arsenic in the Sediment
of Bengal Delta Plain.
D. Chatterjee.
5. Phytoremediation: A Potential Option to Mitigate Arsenic
Contamination in Soil-Water- Plant System.
Indranil Das, Koushik Ghosh and S.K.Sanyal.
6. Dietary Protection against Arsenic Toxicity.
Madhusnata De.
7. Provision of Arsenic-Free Safe Water- an
Appropriate Technology:
Debabrata Ghosh, Ranjan K. Biswas, Morshed
Alam and Anirban Gupta.
8. Arsenic Chemistry in Groundwater in the Bengal
Delta Plain: Implications in Agricultural System.
K. Ghosh, I. Das, S. Saha, G.C. Banik, S. Ghosh,
N.C. Maji and S.K. Sanyal.
9. Chronic Arsenic Toxicity: Health Issues in West
Bengal
D.N. Guha Mazumder.
10. Removal of Arsenic from Drinking Water Using Low
Cost Adsorbents.
Shailesh Gupta and Kamal K. Chaturvedi.
11. Arsenic Free Drinking Water: The Gontra Experience.
Ashok Kundu and Debatra K. Dey.
12. Wind Powered Desalination - Drinking Water from the
Wind.
Charlie Madden.
13. Status of Arsenic Contamination and
Hydrogeochemistry of Deeper Groundwater in Eastern Part of River
Bhagirathi, West Bengal, India.
Abhijit Mukherjee and Alan E. Fryar.
14. Options for Supplying Arsenic Safe Water to the
Community.
Arunabha Majumder.
15. Iron Mediated Solar Oxidation and Removal of
Arsenic: A Household Treatment Option.
P. Mukherjee, J. Jana, S. Chakroborty and D.
Chatterjee.
16. The New Menace in Asia: Arsenic in Groundwater and
its Impact on Community Health.
K.J. Nath.
17. Direct Filtration of Surface
Water.
ZENON Environmental Inc, Ontario,
Canada.
Corresponded by S. Nayak.
18. Journey towards Reduction of Sufferings of the
People of West Bengal from the Clutch of Arsenic.
D.P.Poddar, Arup Chakraborty and Tarak
Banerjee.
19. Overview on Arsenic Contaminated Groundwater and
Mitigation Measures in Nadia District – West Bengal.
B.R. Podder, R. Bhattacharjee and J.
Jana.
20. Epidemiology of Arsenicosis.
D.K.Raut.
21. Arsenic Exposure through Drinking Water Creates Health Problem Due
to Lack of Awareness.
A.
Roy Chowdhury.
22. Alarming Arsenic Attacking Aquifers.
Manabendra Sahu.
23. Arsenic Contamination in Groundwater of
the Bengal Delta Basin: Implications in Agricultural Systems.
S. K. Sanyal and S. K. T. Nasar.
24. Alternate Land Use Option: A Combat Measure to
Reduce Arsenic Loading in Soils of Nadia District, West Bengal.
Dipak Sarkar.
25. Arsenic Hazards in West Bengal: Cause, Effect
and the Remedy.
Mitali Sarkar and Sucharita Manna.
26. Arsenic Removal Kit.
S.
Sukul
IMPACT OF AWARENESS OF ARSENIC ON HEALTH AND
ENVIRONMENT AMONG THE RURAL PEOPLE: A CASE STUDY ON THE VILLAGES OF
NORTH 24-PARGANAS
Pralay O’ Basu, Save the Environment, Prof. R. Chakraborty,Calcutta
University, Ms. Nirapuma Bhattacharya
Thousands of Indian villages still do not have any local source of
drinking water. People often have to walk miles to collect even a pot
of drinking water of dubious quality, adding drudgery of their harsh
lives. About 2.31 lakhs villages or about 40 per cent of the villages
in the country, were designated ‘problem villages’ by the Drinking
Water Mission at the commencement of the sixth plan. Theses villages
either had no potable water source or, if present, the source was far
away from the habitation, or was at a depth of 15m, or at an elevation
of more than 100 m. Some of these sources are even contaminated either
with guinea worm or cholera germs and typhoid pathogens or the water is
chemically contaminated with fluorides and
arsenic.
The massive expansion in exploitation in groundwater resources has high
stress in the ground water system and as a result ground water levels
have declined by 2 to 4 meters. It has been established that excessive
extraction of ground water is a causal factor for arsenic
contamination.
To study the Impact of Awareness of Arsenic on Health and Environment
among the Rural People a survey has been carried out in six different
rural areas of North 24-Parganas of West Bengal – Kamdebkati,
Shimulpur, Raghabpur, Kalitala, Betput and Biswashati, which are
arsenic pollution prone zone. These villages are located on North 24
Parganas of West Bengal. To show the impact of awareness we have chosen
three villages namely Kamdevkati, Shimulpur and Raghabpur where Arsenic
Removal Plant have been installed and three villages namely Kalitala,
Betpul and Biswashati where Arsenic Removal Plant has not been
installed.
To make the study more comprehensible we have alienated the studied
rural community into two categories. The villages where awareness
campaigning has been done and Arsenic Removal Plant is installed we
have categorized them as group I and the villages where awareness
campaigning has not been done and Arsenic Removal Plant has not been
set up we have categorized them as group II. For both the group the
sample size has been taken the same. During the survey it has been
observed that in all the six villages the standard of living and the
educational level of the informants have no significant difference. The
survey reports that the percentage of people of group I using water
from tube well exceeds by 10 % than group II. In group I only 2% people
were found not using any protection shield for arsenic whereas in group
II 71% people were found not taking protection against arsenic polluted
water. The difference between two groups is quite significant despite
of having almost same standard of living and education. Awareness can
bring about some changes in the perception and the following statements
support the words. In group I villages 93 % are aware of the term
“Arsenic” and bear a clear concept on it. In-group II villages 66 % are
aware of the term “Arsenic” but only 5% people have a superficial
understanding of the term. To study it in more details Logistic
Regression method was applied. Thus awareness plays an important role
in changing the perception of the people.
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ARSENIC CONTAMINATION OF DRINKING WATER IN
RURAL AREAS
OF INDIA AND ITS BEARING ON INDIAN ECONOMY
Kaustav Bhattacharyya
Department of English, Karimpur Pannadevi College
Nadia, West Bengal
Water forms a major part of our environment. About 71% of the world’s
water Body only 3% is fresh water. Excessive overhauling has dropped
the water table at a detrimental level. In addition to that rapid
industrialization has caused to the pollution of surface water. But
most alarming at present is the arsenic contamination of drinking
water. The rural people of India are the most to drink this poisonous
water from their tube-wells. Arsenic from rodenticides, larvaecides,
herbicides, as waste from copper industries gets deposited in the
sub-soil or present in parental form in some layer of soil gets
released through some chemical process and dissolves in the water of
the layer. An arsenic- affected person suffers from skin –disease and
can barely stand, walk or hold anything. A large section of this rural
population of India is engaged in Agricultural work. Agriculture is of
immense importance in India’s economic Development programme as it is a
great source of national income (about 18% of Income by exporting
agro-products). Agriculture in India has become very self- Sufficient
and resulted in saving the expenditure of foreign money. It has also
contributed to rapid industrial development through production
–linkage, Demand –linkage and savings & investment –linkage and in
flourishing the Internal market of the nation. Economists may opine
that decrees in Population in an over-populated country like India will
be a blessing but the fact may be otherwise. New markets sprout with
population increase resulting in new Income and investment. If
arsenic-affectation of rural populace spreads like an Epidemic then
there will be massive fall in the number of agro-workers. The
Government will not only have to spend in medical purpose, but also
have to feed these disabled from other sources. The consumer to
producer ratio will Increase which will pressurize the remaining
workers and the ultimate result is that per capita production of agro
or industrial products will be negative. This Condition may appear as a
blow to the golden dream of economic development Of India, if not now
at present but at a near future.
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GEOCHEMISTRY OF ARSENIC IN GANGA SEDIMENT: A
CASE STUDY IN WEST BENGAL, INDIA
S. Chakraborty 1,2, B. Nath2, J. Jana2, P. Mukherjee2 & D.
Chatterjee2
1 Department of Chemistry, Kanchrapara College, Kanchrapara, North 24
Parganas
2 Department of Chemistry, University of Kalyani, Kalyani, Nadia-741235
Arsenic Contamination in groundwater has been envisaged as a global
issue in the perspective of population exposure and area coverage. A
vast alluvium plain (34,000sqkm)has been affected with elevated level
of arsenic in groundwater with high arsenic
concentration(50-500mgL-1).The contamination mostly found in upper
delta plain(UDP) and comprises of younger Ganga sediments. The
lithology is dominated by sand to silty loam to silt with fining upward
sequences. The major identified minerals (Quartz, Muscovite,
Clinochlore chlorite) by XRD do not vary with depth. The organic matter
content in sediment is ~1%.The groundwater chemistry of the affected
area reflects high concentration of HCO3 - , PO4 -3 and NO3 -, SO4 -2,
F- concentrations are low. Field parameters (pH, Eh, DO) which show
that Eh is generally negative, pH is usually near neutral. Adsorption
study of arsenate on pure Muscovite mica shows maxima at pH 5.5.
Therefore weathered mica particles can play an important role in
mobilization/immobilization of arsenic under local reducing condition.
The proper geochemical understanding of controls will help to
demonstrate the future trend of arsenic contamination in Bengal Delta
Plain (West Bengal).
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GEOCHEMISTRY OF ARSENIC IN THE SEDIMENT OF
BENGAL DELTA PLAIN
D. Chatterjee,
Department of Chemistry, University of Kalyani, Kalyani-741 235, India
Dissolved high natural inorganic arsenic is now causing serious threat
to human health in Bengal Delta Plain (West Bengal and Bangladesh). In
West Bengal, the occurrence of arsenic in groundwater is often
exceeding the WHO guideline value (10 ppb) and National Standard
(50ppb) and millions of water wells are now contaminated with arsenic.
The area (~ 70 km north of Calcutta, 22o-24o N, 87o-89o E) covering an
integral part of world’s largest Ganga-Brahmaputra young deltaic
alluvium (lowland Holocene sediment). Filtered (0.45 mm) water and
sediment samples were collected from the field and divided in two sets,
(i) acidified (0.2% HNO3 v/v) for cation analysis, (ii) un-acidified
for anion analysis. [As]T, [Fe]T, As (III) and organic carbon of the
sediments were determined. Results of the contaminated wells reveal
that the waters are in general Ca-HCO3- (pH ~6.7-7.7) type and fresh
(conductivity 350-1290 ms cm-1). The aquifer is anoxic in nature (Eh
< -0.07- -0.34mV) with high bicarbonate (260-740 mgL-1) and redox
sensitive species (As, Fe, Mn, NH4+). Groundwater samples are high in
As (>0.02 ppm), Fe (>0.2 ppm, Fe[II] 0.01-0.2 mmolL-1), Mn
(>0.45 ppm), HCO3- (>470 ppm) and often P (0.59 ppm)
concentration and low in chloride (<55 ppm) concentration. Water
quality indicates that iron-reducing condition is prevailing and
thermodynamically favored process. The alkalinity of the pore water
increases (8.1±0.5 mmolL-1) due to the recharge from Hooghly
river (25 mmolL-1) and this helps to facilitate the breakdown of
organic matter and this ultimately leads to dissolution of iron oxides.
High groundwater temperature (26-31oC) and pCO2 further enhance the
microbial processes that responsible for local reducing condition.
PHREEQC programme reveals that the groundwater is supersaturated with
calcite, siderite and goethite. This means the iron hydroxide and
carbonates are playing a vital role in mobilizing redox sensitive
species (As) in groundwater. Sediment organic carbon (1%) and [As]T
(17.5 mgkg-1) are relatively low and there was no buried peat in the
sediment. From the study it may be concluded that organic matter has
driven the microbiological process rather formation of peat, which has
been previously hypothesized.
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PHYTOREMEDIATION: A POTENTIAL OPTION TO MITIGATE
ARSENIC CONTAMINATION IN SOIL-WATER- PLANT SYSTEM
Indranil Das, Koushik Ghosh and S.K.Sanyal
Bidhan Chandra Krishi Viswavidyalaya,
Mohanpur – 741 252, Nadia, West Bengal
Arsenic is of great environmental concern due to extensive
contamination of groundwater in the Bengal delta basin with this toxin,
thereby causing carcinogenic toxicity to millions of people. Soil
contamination with arsenic input through the vehicle of contaminated
groundwater being used for irrigation, may prove detrimental to plant
through its uptake to the toxic level. Indeed, the possibility of such
toxin entering the human food web, along with biomagnifications up in
the food chain, through plant uptake of arsenic is of immediate
concern. In this regard, phytoremediation is a developing technology
that offers a potential avenue to address the problem of arsenic
contamination of soil-crop system. In this context, however, the need
of the hour is to develop reliable and cost-effective phytoremediation
technologies capable of bringing down arsenic in groundwater (and in
soils as well) to environmentally acceptable levels.
The success of such remediation would evidently depend on establishing
a selected plant community. For this, a systematic search for
phytoaccumulating or phytoexcluding plant species is necessary.
Although a beginning has been made in this regard to identify arsenic
accumulating plant species at BCKV over the past 4-5 years period (as
well as elsewhere), much more sustained research studies need to be
undertaken to focus attention on these aspects in order to achieve
tangible success. Some of the techniques in this field which may prove
useful include phytodegradation (the process in which the given plant
species are capable of metabolizing and destroying the contaminant
within the plant tissues), phytovolatilization or biotransformation
(the process employing microorganisms and plants to transform the
toxicants into the volatile forms to escape to the atmosphere),
rhizofiltration (the process in which plants, used for clean-up,
accumulate the toxicants), etc. Continued research on these aspects of
phytoremediation is essential.
Several weed species, namely Ludwigia parviflora, Filmbristylis sp.,
Ageratum conyzoides, Eleusine indica, etc., which were identified by
us, showed promise of accumulating substantial amounts of arsenic
(e.g., 50 times or even more) in their plant biomass when grown in the
arsenic-affected areas, in comparison with the situation where such
weeds grew in arsenic-free areas under observation. The latter may
prove attractive due to its relative cost-effectiveness, coupled with
its aesthetic nature, namely the use of plants for “clean-up”
activities.
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DIETARY PROTECTION AGAINST ARSENIC TOXICITY
Madhusnata De
Associate Professor, Dept. of Genetics
Vivekananda Institute of Medical Sciences
Ramakrishna Mission Seva Pratishthan
99, Sarat Bose Road, Kolkata-700026
In West Bengal, India earlier studies has recorded enhanced arsenic
content, ranging between 0.2 to 0.64 mg/L drinking water from shallow
tube wells in 5 districts (Chakravarty and Saha, 1987). During the past
years, increased arsenic content, of as much as 0.8 mg/L has been
recorded in tube well water from 159 villages in 7 more districts of
West Bengal. The human safety limit permissible by the WHO is 0.05
mg/L. Almost 30% of the villagers drinking the contaminated water
showed arsenicals dermatitis and keratosis, in addition to other
symptoms of arsenic poisoning (Anandabazar, 1993). The worst hit areas
are Malda, Mursidabad, Nadia, Hooghly, Howrah, Burdwan, South and North
24 Parganas, as identified by Geographic Information System (Statesman,
2000). The average concentration of arsenic in groundwater is reported
to be 0.2mg/L, reaching a maximum of 3.7 mg/L in the affected areas
(Chakravarty et al 1998).
The extensive arsenic poisoning of the human population in West Bengal,
India (Mandal et al, 1996) and adjoining Bangladesh (Dhar et al, 1997)
through high levels of arsenic in drinking water from tube wells has
led to investigation on different methods to prevent harmful effects.
Attempts are being made by our group to protect against the effects of
arsenic in drinking water through dietary supplementation.
The problems of protection against exposure to arsenic through drinking
water has assumed considerable importance, due to the widespread
effects of arsenic poisoning of large human populations numbering
several millions in West Bengal and Bangladesh. The effects of
environmental toxicants like arsenic were related to life style and
also to different kinds of addiction.
About 5.3 millions people in West Bengal live in areas where arsenic
concentration is above the permissible limit. So, dietary protectants
can only serve as useful remedies to defend against the ill effects of
arsenic.
Tea is well-known beverage, brewed from leaf of Camelia sinensis and
widely consumed throughout the World. Commercial tea is available in
several forms, amongst which black tea is most prevalent in India and
green tea in China and Japan. Consumption of tea has been associated
with anti-mutagenic and possible anti carcinogenic effects (Yang 1997,
Yang and Wang, 1993). Black tea was used in reducing the cytotoxic
effects of inorganic arsenic in mice when given as a regular
supplementation. This work is of special importance in view of the
widespread exposure of human population in several districts of West
Bengal, India and Bangladesh to arsenic through drinking water from
tube wells.
The mode of protection may be attributed to the combined antioxidant
and scavenging properties of the components of tea infusion (Mukerjee
et al, 1999). The results were significant in view of the widespread
effects of arsenic toxicity on human populations exposed to arsenic
through drinking water. Black tea infusion is a common everyday drink
and can be utilized for protection of human population.
A total of 100 cases from VIKAS KENDRA, Atghara, aged between 13 to 68
years, who were drinking arsenic contaminated water since their birth,
are the subjects of the present study. Oral smears were obtained and
the percentages of micronuclei were
determined.
Concentration of arsenic in hair and nail were analyzed from those
individuals. Percentage of micronuclei was increased in exposed group
and mitotic index was low in these groups.
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PROVISION OF ARSENIC-FREE SAFE WATER - AN APPROPRIATE
TECHNOLOGY
Debabrata Ghosh, Ranjan K. Biswas, Morshed Alam, Anirban Gupta
Environmental Engineering Cell, Civil Engineering Department,
Bengal Engineering and Science University, Shibpur, Howrah - 711103
Arsenic has been found in groundwater in many parts of the world &
is posing threat to human health. It is a serious problem in 79 blocks
of 9 districts of West Bengal. In the seventies, the use of surface
water was replaced by heavy dependence of ground water in West Bengal
in order to overcome the problem of microbiologically unsafe untreated
surface water. Surface and dug well water sources cannot be used either
for drinking or for cooking purpose because these are not properly
preserved. A large portion of these arsenic-affected areas are rural
& there are no other alternative source of safe water like pipeline
water supply & as a result, people living in these areas are fully
dependent on tube-well water, which often is contaminated with higher
levels of arsenic. The reported clinical manifestation resulting from
ingestion of arsenic contaminated drinking water includes weakness,
respiratory problem, keratosis, melanosis, peripheral neuropathy &
even cancer. Since people in these areas mostly belong to
low-income group having poor nutritional dietary intake, they are very
much affected by arsenic related diseases. Provision of safe water is
of urgent necessity in the arsenic-prone areas. Before any long-term
solutions like treatment and supply of surface water can be
implemented, spot treatment units to treat the contaminated tubewell
water is of great help to save millions of people from arsenic
toxicity. There are many processes in use for removal of arsenic from
groundwater like chemical precipitation, adsorption, ion exchange &
membrane filtration. BESUS (Bengal Engineering & Science
University, Shibpur) has developed a process based on adsorption of
arsenic from water by activated alumina. BESUS has started working in
this field in 1996 and has been able to install about 140 arsenic
removal units in West Bengal till date, which are running successfully,
some of which are running for more than eight years. Many of the units
are providing safe drinking & cooking water to more than 150
families in each case. BESUS promotes community participation for
long-term sustainability where local water committees take charge of
operation and maintenance of the filter & tube well. Community
based arsenic removal filters, which are in use, has been made
sustainable by mass awareness campaign taken up by BESUS for use of
arsenic free safe water. The technology adopted by BESUS is user
friendly and media (activated alumina) can be regenerated at low cost
for reuse. Many of the arsenic-patients are showing significant
improvement in their health condition. The health & condition of
the arsenic-affected patients improved significantly after consuming
arsenic-safe water. This paper describes one of the cost effective
technology for supplying of arsenic free safe water for rural mass.
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ARSENIC CHEMISTRY IN GROUNDWATER IN THE
BENGAL DELTA PLAIN: IMPLICATIONS IN AGRICULTURAL SYSTEM
K. Ghosh, I. Das, S. Saha, G.C. Banik, S. Ghosh, N.C. Maji and S.K.
Sanyal
Bidhan Chandra Krishi Viswavidyalaya, Mohanpur – 741252, Nadia, West
Bengal
Arsenic (As), a toxic trace element, is of great environmental
concern due to its presence in soil, water, plant and animal continuum.
Arsenic in terrestrial environment may have had its origin in natural
and anthropogenic sources. Arsenic contamination of groundwater in the
Gangetic alluvial zones of West Bengal has assumed the proportion of a
drinking water-related disaster in recent years with reports of arsenic
related health hazards for millions of people. The groundwater As
concentration (50 – 1600 mg/L), reported from the affected areas of
West Bengal, are several orders of magnitude higher than the stipulated
Indian standard for the permissible limit in drinking water (50 mg/L),
which is also the maximum acceptable concentration, MAC, for drinking
water in Bangladesh, India and several other countries), as well as the
WHO guideline value (10 mg/L). The arsenic loading of the groundwater
which is used as irrigation source varied from 0.06 to 0.53 mg/L in
Nonaghata mouza of the Haringhata block of Nadia district in West
Bengal. A high degree of such contamination was also found in different
parts of the affected-belt, to name a few, Gotera and Ghentugachi
mouzas of Chakadaha block of Nadia district (ranging from trace to 0.89
mg/L); Ambikanagar, Chakla, Iajpur and Chyangdana villages under
Deganga block of North 24- Parganas district of West Bengal (varying
from 0.05 to 0.50 mg/L), etc. by a group of researchers at Bidhan
Chandra Krishi Viswavidyalaya.
Soil, though an important sink for arsenic, may nevertheless facilitate
its access to plant through leaching, methylation or erosion. The clay
fraction, iron and aluminum oxide and organic carbon pool in soil have
frequently been implicated in the sorption of different species of
arsenic by soils. Sequential extraction of soil arsenic helps one to
differentiate between arsenic that is readily labile, and accessible to
plant uptake, and that which is bound strongly by the soil components
in soil matrix.
Some of our research studies, conducted at the selected affected areas,
revealed that the total and Olsen extractable (i.e., 0.5M NaHCO3, pH
8.5 – extractable As which constitutes the soil As pool amenable to
plant uptake) arsenic varied from 8.4 mg/kg to 24.3 mg/kg and from 2.90
mg/kg to 15.8 mg/kg, respectively, in the affected soils of West
Bengal. The soil arsenic contents of these areas were generally higher
than those reported for the soils of several other countries like
Argentina, China, Italy, Mexico, France, Australia, etc.
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CHRONIC ARSENIC TOXICITY: HEALTH ISSUES IN WEST
BENGAL
D.N. Guha Mazumder
Member, Task Force on Arsenic Govt. of West Bengal
Professor and Head Dept. of Medicine and Gastroenterology (Retd.)
Inst. Post. Grad. Med. Edu. & Res. Kolkata – 700 020.
Many aquifers in various parts of the world have been found to be
contaminated with arsenic (As) at concentration above 50
µg/l. Of these the most noteworthy occurrences are in large
areas of West Bengal (India) and Bangladesh, Taiwan, Northern China,
Hungary, Mexico, many parts of the USA, Chile and Argentina.
Chronic arsenic toxicity due to drinking arsenic-contaminated water has
been one of the worst environmental health hazards, affecting West
Bengal since the early eighties. It is suspected that 6 million
people are exposed to As contaminated water in 72 blocks of 8 districts
of the state, the highest As level reaching up to 3400 µg/l (safe
level < 50µg/l). The source of contamination is
suspected to be geological. Detailed clinical examination and
investigation of 248 such patients revealed protean clinical
manifestations of such toxicity. Over and above hyperpigmentation
and keratosis, weakness, anaemia, burning sensation of eyes, solid
swelling of legs, liver fibrosis, chronic lung disease gangrene of
toes, neuropathy, and skin cancer are some of the other manifestations.
A cross-sectional survey involving 7683 participants of all ages was
conducted in an arsenic-affected region between April 1995 and March
1996. Out of a population of 7683 surveyed, 3467 and 4216 people
consumed water containing As below and above 0.05 mg/l,
respectively. Except pain abdomen the prevalence of all other
clinical manifestations tested (e.g., pigmentation, keratosis,
Hepatomegaly, weakness, nausea, lung disease and neuropathy) were found
to be significantly higher in As exposed people (water As >
0.05mg/l) compared to control population (water As level <
0.05mg/l). The prevalence of pigmentation and keratosis,
hepatomegaly, chronic respiratory disease and weakness rose
significantly with increasing arsenic concentrations in drinking
water. The respiratory effects were most pronounced in
individuals with high arsenic water concentrations who also had skin
lesion. Therapy with chelating agent DMSA was not found to be
superior to placebo effect. However, therapy with DMPS caused
significant improvement of clinical condition of chronic arsenicosis
patients.
However, this medicine is not available in India and is very costly.
Supportive treatment could help in reducing many symptoms of the
patients. People should be advised to stop drinking As contaminated
water or exposure to As from any other source. The various
clinical manifestations should be treated symptomatically.
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REMOVAL OF ARSENIC FROM DRINKING WATER USING
LOW COST ADSORBENTS
Shailesh Gupta and Kamal K. Chaturvedi
Department of Biochemistry
Govt. Model Autonomous Holkar Science College Indore (M.P.)
Arsenic is a commonly occurring toxic metal in natural ecosystem.
Inorganic arsenic is an established human carcinogen. Inhalation of
arsenic dust particles and ingestion from drinking water are the main
sources of human exposures. The purpose of this research is to convert
the agricultural wastes, bagasse and bagasse fly ash which are
low-cost, ecofriendly, renewable and widely available wastes into
inexpensive and effective adsorbent materials for arsenic REMOVAL from
drinking water. Adsorption by these materials can be used as an
alternative to conventional methods which are usually associated with
high costs and thus do not suit the needs of developing countries.
Batch experiments for As(III) and As(V) with bagasse and its fly ash
were conducted as a function of adsorbent dose, contact time, adsorbate
concentration and pH to establish optimum conditions for remediation.
Bagasse removes 86.3% and bagasse fly ash removes 98% of arsenic from
its initial concentration of 500mg/L. RESULTS WERE FURTHER CONFIRMED BY
SEM & XRD.
Keywords – Arsenic, bagasse, bagasse fly ash, drinking water.
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ARSENIC FREE DRINKING WATER: THE GONTRA EXPERIENCE
Ashok Kundu and Debatra K. Dey
Rishi Bankim Chandra College & Srikrishna College
West Bengal
Providing arsenic free drinking water to vast rural masses in eight
contaminated districts of West Bengal is a major challenge to the
planners, policy makers and executors. Both the state and market are
virtually unable to supply such basic requirements for saving the human
lives. Gontra, a small village in South Nadia is a unique example
of collaboration between Bengal Engineering College, NGO, Co –
Operative society and local communities to provide arsenic free
drinking water to the poor villagers at minimum cost for the last five
years. The paper attempts to find out the role of local
institution and community behind its success. It will try to
enquire about advantages, disadvantages and the replicability of such a
community – based model.
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WIND POWERED DESALINATION - DRINKING WATER FROM THE WIND
Charlie Madden
Managing Director
Wind - Water Pty Ltd.Australia
We are in the process of developing the first version of Wind - Water
based on raw distillation that will produce 400 litres a day of pure
drinking water. This will be 98% arsenic free.
We are then going on to increase the output to maybe 80,000 litres a
day by a different approach. The power comes from a 10kW vertical axis
wind turbine. The photo of the half size prototype is attached. In the
current machine being built, this drives a vertical shaft at 100 rpm
which drives the pumps, fans and joule heater on the ground. The ground
equipment is in stainless steel, the rotor in carbon fibre epoxy and
the tower in mild steel. The wind range is 4 - 12 m/s after which it
shuts itself down. The pumps load the churn which heats the water. The
fans lift off the vapour which condenses on passing through a heat
exchanger cooled by the water coming in, which it heats up. A patent
has been applied for. We are a small company in Adelaide, and any help
would be welcome.
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Status of arsenic contamination aND
hydrogeochemistry of deeper groundwater IN eastern part of river
Bhagirathi, West Bengal, India
Abhijit Mukherjee and Alan E. Fryar
Department of Geological Sciences
University of Kentucky, Lexington, USA
Formidable concentrations of arsenic (As) in groundwater of the Bengal
basin have been acclaimed as the greatest mass poisoning in human
history. Previous workers have identified elevated levels of As mostly
in the shallower Holocene aquifer of Bengal. Many workers have
suggested that groundwater at depth of 100m or more below surface is an
alternate safe potable water source. We are investigating this
hypothesis and contradicting the traditional belief. Our study
includes an area of about 12,000 km2 of the districts of Murshidabad,
Nadia, North and South 24 Parganas.
The study area is predominantly underlain by a single regional aquifer
system with multiple discontinuous aquitards in the southern part
(south of mid North 24 Parganas). There are some deeper isolated
aquifers with distinct chemistry from this main aquifer. Based on the
study of deeper groundwater from the regional aquifer, we observed that
61% and 33% of our locations have As concentrations ³ 10 ppb and
³ 50 ppb, respectively. The As is mostly present in dissolved
phase (£ 0.45mm) with 64% of it as more hazardous As (III).
Elevated As was not found in deeper water of South 24 Parganas. The
highest concentration of As recorded is 223 ppb. The water has very low
dissolved oxygen (0.49 to 2.32 ppm), pH of 6.8 to 8.1, SC ranging from
619 to 1810 ms/cm, and alkalinity (as HCO3-) from 367 to 649 ppm.
Fe(II) is mostly £ 2 ppm but may reach 7 ppm. The median Fe value
(1053 ppb) for deeper wells (³100m) is less than the median for
shallower wells (1505 ppb). The lack of correlation between As and Mn
(r2 = 0.05) and weak correlation with Fe (total) and Fe(II) (r2 = 0.22
and r2 = 0.41) suggests that As concentrations in the deeper aquifer
may not reflect As sorption onto Mn minerals and weak sorption on
reduced Fe minerals, which is contrary to previous theories. A Piper
plot indicates that the predominant hydrochemical facies is Ca2+–HCO3-.
Some trends of salt-water mixing and CaCO3 dissolution have also been
noted. Na+ was found to be the dominant cation in some wells in North
24 Parganas. Median values of Ba and Sr were 196 and 377 ppb,
respectively. Sr varies significantly with Ca + Mg (r2 = 0.54),
indicating a possible contribution of Sr from Ca-Mg mineral
weathering.. Concentrations of other trace metals (Be, Co, Li, Ni, Sb,
Se, V, U and Th) were below detection limits. While PO43- and S2- were
not detected in any of the wells, CH4, SO42- and NH4+ were observed in
several wells. 18O concentrations averaged -4.8‰ standard mean ocean
water (SMOW) and d2H concentrations averaged -29.9‰ SMOW. Values of 18O
plotted versus d2H scatter around the global meteoric water line,
indicating recharge from precipitation with some effects of
evaporation. 18O and d2H generally became more positive toward the
south. 18O values generally fall between –3‰ and –6‰, which is
consistent with water < 3 ka old (P.K.Aggarwal et al., IAEA TC
Project BGD/8/016, 2000).
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Options for supplying arsenic safe water
to the community
Arunabha Majumder
Director- Professor
Dept. of Sanitary Engineering
All India Institute of hygiene & Public Health, Kolkata
Supply of water from surface water sources e.g. river, lake etc. after
purifying the water though conventional treatment
(coagulation-flocculation-sedimentation-rapid sand
filtration-chlorination). The water is distributed through pipe-network
system.
Installing deep tubewells for abstracting water from arsenic free
aquifers. The tubewells need to be sealed effectively during
installation so as to prevent seepage of arsenic contaminated water
from upper aquifer to lower aquifer.
Collection of water through rain water harvesting and supplying the
same after appropriate treatment. Pond water can also be used as
arsenic free water after treating it by HRF-SSF technique.
Supplying arsenic safe water after removing arsenic through different
treatment options. Such system could be for domestic as well as for
community (hand pump attached).
In West Bengal, around 1900 hand pump attached arsenic removal units
(ARU) have been installed under different programmes. Following
principles were adopted by different manufacturers.
i. Co-precipitation
(AIIH&PH model) ---
Chemical Use : Bleaching powder and alum.
Process : Flush mixing, coagulation flocculation - sedimentation -
upflow filtration.
ii.
Adsorbtion ---
Chemical Use :
i)
Activated Alumina
ii)
Ferric hydroxide
Different graded activated alumina and ferric hydroxide are used. Some
manufacturers import media for manufacture of ARU.
iii.
Ion-Exchange : Use of "Bucket of Resin" for removal of arsenic.
iv. Membrane
filtration Technique / Reverse Osmosis.
Domestic units for removal of arsenic comprising of co-precipitation
and adsorbtion (AA) are in use in West Bengal.
Community based management system is being developed by AIIH&PH for
operation and maintenance of hand pump attached arsenic removal units
under ICEF-AIIH&PH project. NGO partners are working for arsenic
problem mitigation programme.
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IRON MEDIATED SOLAR OXIDATION AND
REMOVAL OF ARSENIC: A HOUSEHOLD TREATMENT OPTION
P. Mukherjee, J. Jana, S. Chakroborty, D. Chatterjee
Dept. of Chemistry. University of Kalyani
Arsenic (As) has now been recognized as most widespread natural
contaminant and threatens the health of millions of people worldwide.
Many large and small communities experience As contamination in
groundwater and/or drinking water supplies in many parts of the world
and significantly in south-east Asia. The scale of the problem is
serious and unprecedented in West Bengal and Bangladesh (Bengal Delta
Plain, BDP) both in terms of human exposure and geographical area
coverage where As concentration in contaminated wells exceeds both WHO
guideline value (10 mgL-1) and stipulated National standard (50 mgL-1)
for both Bangladesh and India. Dissolved forms of As in the BDP water
include arsenite (~50-70%), arsenate (~30-50%) and ultra-trace amount
of MMA (monomethylarsonic acid) and DMA (dimethylarsinic acid).
Arsenite and arsenate species can interchange depending on redox
potential (Eh), pH and biological processes. Conventional treatment
techniques to remove As from groundwater are cost prohibitive and
difficult to practice in rural areas of BDP. Instead of using hazardous
chemicals (e.g. chlorine, ozone in conventional method) As from
groundwater can also be removed by exposure to sunlight (solar
oxidation) in presence of dissolved iron (Fe) and a chelating agent
(citrate, naturally available) followed by filtration with cloth or
simple decantation. The technique is user friendly, low cost and easy
to perform by the rural mass of the BDP.
Key-words- solar oxidation, iron, chelating agent, arsenite, arsenate,
MMA, DMA
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THE NEW MENACE IN ASIA:
ARSENIC IN GROUNDWATER
AND ITS IMPACT ON COMMUNITY HEALTH
Prof. K.J. Nath
Chairman, Arsenic Task Force, Govt. of West Bengal, India
President, Institute of Public Health Engineers, India
Member, Scientific Advisory Board & SEA Regional Co-ordinator,
International Forum on Home Hygiene, Geneva
Principal Scientific Advisor, Sulabh International Social Service
Organization
Reports from as many as 25
countries show mild to severe contamination of Groundwater with
Arsenic. The countries include Argentina, Australia, Bangladesh,
Cambodia, Canada, Chile, China, Greece, Hungary, India, Japan, Laos,
Mexico, Mongolia, Myanmar, Nepal, New Zealand, Pakistan, Peru,
Philippines, Romania, South Africa, Taiwan, Thailand, United States of
America and Vietnam.
Arsenic contamination in
groundwater has emerged as a major water quality problem causing
serious health hazards in West Bengal & Bangladesh, where vast
areas have been affected in recent years. Though a scientific
epidemiological assessment of the problem is yet to be made, a major
portion of the population in these countries are living in the
hydrogeologically risk zone. The present crisis is primarily due to
geomorphological reasons, though there have been reports of
anthropogenic contamination of water & air from some countries
including China. The commonly reported symptoms of chronic arsenic
poisoning include hyperpigmentation, dipigmentation and keratosis. Skin
cancer & internal cancer can also occur. The transfer of arsenic
from soil to water and vice versa is dependent on soil water
interaction. The mechanism of the Arsenic release in the ground water
is not well understood and its impact on community health and the
disease burden associated with the same are yet to be ascertained. An
effective plan of action for combating the problem in the affected
countries would require a complete understanding of the possible causes
and a realistic estimation of the extent & magnitude of arsenic
contamination and its possible health effects.
The paper
presents an overview of the problem of arsenic contamination in
groundwater in India, Bangladesh & other South East Asian
countries. The hydro-geological causes and the extent & magnitude
of the problem have been discussed. Various issues related to Arsenic
contamination, eg. release and spreading mechanism of arsenic, effects
of arsenic on human health, remedial action & technology options
etc have been discussed in the context of experiences of various
organizations in these countries. The problem of water quality
surveillance, setting of national Standard of arsenic concentration in
ground water and the cost and other related problem of enforcing the
same have also been discussed.
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DIRECT FILTRATION OF SURFACE WATER
ZENON Environmental Inc
Oakville Ontario Canada L6M4B2
Corresponded by Mr. Suresh Nayak
Business Development Manager. South-East Asia.
The City of Scottsdale, Arizona has historically obtained its Salt
River Project (SRP) water allotment as treated water from the City of
Phoenix Verde Water Treatment Plant (WTP). However, this agreement
expires in 2005, and the City has decided to build its own WTP.The new
plant will require reliable treatment of challenging surface water from
the Arizona Canal, which has a TSS range between 18 and 59 mg/l, and a
pH range of 7.7 to 8.5(average pH is 8.1). Turbidity and TOC are
between 5-25 NTU and 2-3.6 mg/l, respectively. Water temperature varies
between 10 and 30°C. The arsenic concentration can range from 4-20
µg/l in the raw water.
Therefore an additional water quality objective is to reduce the
arsenic concentration to below the revised US EPA MCL of 10 µg/l
using coagulant addition.
In January 2000, Scottsdale’s City Council authorized a pilot program
to evaluate the latest water treatment technologies. Following the
pilot testing, ZENON’s ZeeWeed® 500 series membrane technology was
selected based on a comprehensive present worth evaluation. The latest
ZeeWeed® 500 series product, the ZeeWeed® 500d, was later found
to offer considerable additional cost savings over the module first
piloted. Subsequent testing verified its performance. Final operating
parameters were as follows:
• Flux –30 GFD
• Recovery – 90%
• 15 mg/L ferric salt
Chaparral WTP Treated Water Pilot Results
Raw Water
Filtered Water
Turbidity (NTU)
8.0
<0.03
TOC (mg/L)
2.9
2.0
TSS mg/L)
38
0
As (µg/L)
6.6
<1.8*
*membrane filtration + 15mg/L ferric sulfate coagulant.
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JOURNEY TOWARDS REDUCTION OF SUFFERINGS OF THE
PEOPLE OF WEST BENGAL FROM THE CLUTCH OF ARSENIC
D.P.Poddar, Arup Chakraborty & Tarak Banerjee
West Bengal Voluntary Health Association
19,A Dr. Sundari Mohan Avenue, Kolkata -700014
The contamination of arsenic in the ground water in various districts
of West Bengal, including the city of Kolkata has become the major area
of concern. Approximately the arsenic effected population in West
Bengal touches about 4 crores 20 lakhs. In seventy six blocks of
nine district of West Bengal arsenic contamination in drinking water
have gone to the extent of 0.05 mg which is much beyond the WHO
permissible limit 0.01mg/lt. Arsenic contamination in ground water of
West Bengal has turned to be the greatest arsenical calamity of the
world. West Bengal Voluntary Health Association responded to the need
way back in the year 2000.
WBVHA initiated its activity towards arsenic mitigation program in the
district of Malda , N- 24 Pargana, Nadia and Murshidabad with the
assistance of India Canada Environment facility in collaboration with
All India Institute of Hygiene and Public Health . WBVHA in
consultation with different experts felt the need to aware and
sensitize the community people on arsenic and the probable consequences
through various media. In relation to sensitize various sections of the
community, 10 trainings for the paramedics were organized in the above
mentioned 4 districts of West Bengal.
The objective behind carrying out these activities is to sensitize
maximum number of effected population as well as to create an alternate
support system and build up a sense of ownership to combat this menace.
With the activities still in full swing, the impacts of the various
programs have started pouring in.
For consolidation of the program as well as the sustainability point of
view, WBVHA planned to create or strengthen community based groups,
preferably Self Help Groups, and through these grass root groups more
and more people will be sensitized. With an aim to provide
more and more number of people, the safe drinking water, in the arsenic
effected area, as well as adding partially towards rural economy, WBVHA
plan to help local potter to make low cost domestic filter and market
in the effected area.
We believe that even though the journey towards reduction of the
sufferings of the small section of the people has just began and the
gravity of the problem is too heavy, however with the kind assistance
of all sections of the people, changes in the scenario is inevitable.
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OVERVIEW ON ARSENIC CONTAMINATED GROUNDWATER AND
MITIGATION MEASURES IN NADIA DISTRICT – WEST BENGAL
B.R. Podder, R. Bhattacharjee, J. Jana.
P.H. Engineering Dte.
Nadia Division,
Government of West Bengal.
D.C. Building, 1st Floor,
Kalyani, District – Nadia.
The district Nadia lies in the alluvial deltaic plain of Ganga and its
tributaries. Its latitude in between 230 52’ 30” N – 230 05’ 40” N and
longitude in between 880 08’ 10” E – 880 48’ 15” E. Ground water
development has started extensively in the early 70s as a results of
green revolution to encounter the water demands for irrigation, as well
as human consumption. Arsenic poisoning was sporadically reported in
early 80s in few pockets (Nadia, Murshidabad, Maldah, and South 24
Parganas) of West Bengal. Presently the risk population in the rural
areas is 38.53 lakhs covering all the blocks (seventeen) of Nadia
District. The health affect (mostly skin lesions, arsenicosis etc.) was
attributed to prolong consumption of arsenic contaminated ground water
with elevated level (As >50 mgl–1). The arsenic related health
problems show a decreasing trend as soon as population is provided with
arsenic safe drinking water.
Arsenic contaminated well normally (³50 mgl –1) occur within the
depth range of 20 – 100 m bgl, while more than 100 m bgl tube well are
relatively safe (<50 mgl–1). It is observed that shallowest well
(< 20 m) also tend to have low arsenic concentration. Similarly,
more than 100 m bgl the arsenic contamination is higher than 50 mgl –1
. Several remedial options have been suggested by the scientist and
engineers so far and adopted as well as implemented by the subsequent
action plans for supply of safe drinking water.
In addition to district level laboratory some laboratories have been
set up under joint Action Plan at the doorstep of rural people. The
options like Arsenic Treatment Units over hand pump fitted tube wells,
sinking of deeper aquifer tube wells and also ring wells have been
implemented as mitigation measures by the P.H.E.D. Domestic arsenic
removal filter has also been developed and being utilized by the rural
people under Joint Plan of Action of Government of West Bengal and
UNICEF. Another option like pipe water supply scheme with Arsenic cum
Iron Removal Plant has also found to be satisfactory.
In this district so many water bodies like lakes, ponds, rivers etc.
are commonly available and free from arsenic. For long term mitigation
measures surface water is the only safe alternative option for drinking
as well as domestic purpose. Some surface water based water supply
schemes are being prepared for implementation.
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EPIDEMIOLOGY OF ARSENICOSIS
D.K. Raut
Professor, Dept. Of Epidemiology
AIIH & PH, Kolkata-73
Arsenic occurs
naturally in all environmental media and usually presents in the form
of compounds with sulphur and with many metals. The average
concentration in the earth's crust is about 2mg/kg. Due to its natural
occurrence, humans are universally exposed to arsenic in various forms.
Exposure of general population occurs mainly through arsenic present in
food and drinking water. In some areas, the natural high arsenic
content of the drinking water above WHO permissible limit of 0.05 mg/l
(50ug/l) has caused endemic, chronic arsenic poisoning. In the humans,
the total daily intake of arsenic is greatly influenced by the amount
of seafood in the diet, and consumers may reach several thousands ug.
of total arsenic per day. However, 85-95% of the arsenic present in the
marine products is present as the much less toxic, organic compounds.
Environmental
arsenic exposure has received attention primarily because of disease
resulting from ingestion of water containing inorganic arsenic. Disease
manifestations have been those of chronic arsenic poisoning, examples
include nonmalignant cutaneous changes such as hyperpigmentation and
hyperkeratosis, skin cancers,"Black foot disease (a form of arsenic
induced peripheral vascular insufficiency leading to gangrene),
peripheral neuropathy plus hematopoetic, renal and hepatic toxicity.
The classic
description of arsenic poisoning relies on reports of suicidal or
homicidal arsenic ingestion. The cardinal features of acute or subacute
arsenic poisoning are gastrointestinal e.g. nausea, vomiting, abdominal
cramps and diarrhea that may be bloody, chronic disease, such as
peripheral neuropathy, can also follow acute exposures.
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ARSENIC EXPOSURE THROUGH DRINKING WATER
CREATES HEALTH PROBLEM DUE TO LACK OF AWARENESS
A. Roy Chowdhury
Regional Occupational Health Centre (E)
(Indian Council of Medical Research)
Block DP, Sector V, Salt Lake City,
Calcutta – 700 091, INDIA.
Out of eighteen
districts in West Bengal, nine districts are severely affected by
ground water of high arsenic content. This arsenic contaminated water
is used by the rural villagers. Most of the affected villages are
Nadia, Murshidabad, 24-parganas (N&S). Large number of community is
affected due to arsenic exposure through drinking water. This
particular environmental calamity was first noted in the year 1981 by a
group of biomedical scientists of School of Tropical Medicine,
Calcutta. The identification of the arsenic exposed health impairment
was first noted by Prof. K.C. Saha. The main feature of this arsenic
exposure is known as arsenicosis. Skin pigmentation (rain drop), mild
keratosis are the early diagnostic manifestation in arsenicosis. In
severe cases, enlargement of liver, which is supported by increased
levels of SGOT, SGPT along with the keratosis in palm and sole, nodular
enlargement and different pattern of neuropathy were seen among the
chronic exposed person.
In this context,
some measures may be undertaken to reduce the arsenic toxicity and for
that awareness generation is highly essential. In the beginning of this
awareness, one must know the nutrition supplementation, i.e. high amino
acid containing cereal, vegetables, along with antioxidants. Secondly,
to avoid the use of arsenic contaminated water in cooking and drinking
purpose, low cost home made filter may be used for getting arsenic free
water. Therefore, some simple and home made technology certainly reduce
the arsenic toxicity. The present discussion regarding the awareness
among the community will certainly be helpful to avoid arsenic exposure.
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ALARMING ARSENIC ATTACKING AQUIFERS
Manabendra Sahu
Dept. of Chemistry
Karimpur Pannadevi College, Nadia, West Bengal
Arsenic is a metalloid. It is very fatal for human if consumed. Used as
an Insecticide, or wastes from industries containing arsenic gets
deposited in the sub–soil or as present from in pyrites layer, due to
some chemical Reaction the layer disrupts and arsenic gets mixed with
water. It is soluble in Water and cannot be observed in naked eye. It
is present in two oxidation state +5 and +3, of which the latter is
more lethal.
According to W.H.O. the permissible limit of arsenic is 10 microgram
per litre of drinking water. If taken for a long time, a person suffers
from Arsenicosis: Blackish-grey spots appear on the skin (Melanosis),
the skin slough and Roughens (Keratosis). Thereafter the patient
suffers from Gastroenteritis and Liver, Kidney, lungs start to
malfunction and possibility of cancer of skin and Lungs becomes more.
At present nine districts of West Bengal are arsenic Affected where
some water samples show that the limit is above 25 times than the
permissible limit.
Arsenic reacts with-SH group of enzyme and defunctions it. The energy
realized from the cell due to Kreb`s Cycle is disturbed. Arsenic reacts
with the Enzyme called pyruvate dehydrogenase and dysfunctions it by
forming a Complex compound. Arsenic hinders the synthesis of ATP in the
bio-chemical Process. Protein is coagulated due to presence of a large
amount of arsenic.
No medicine has yet been discovered to fully cure a patient suffering
from Arsenicosis. Drinking safe water, some physical exercise as
recommended by the physician, intake of nutritious food is some of the
remedial measures. Surface water, any water other than ground water,
such as rainwater and water from dug wells are free from arsenic.
Government should frame and implement Laws regarding digging of
tube-wells at anywhere and should arouse Consciousness among the people
against the evil of arsenic.
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ARSENIC CONTAMINATION IN GROUNDWATER OF THE BENGAL
DELTA BASIN: IMPLICATIONS IN AGRICULTURAL SYSTEMS
S. K. Sanyal and S. K. T. Nasar
Bidhan Chandra Krishi Viswavidyalaya,
Mohanpur-741252, Nadia, West Bengal
Arsenic contamination in groundwater has been reported from time to
time from West Bengal (India) and countries like Bangaladesh, USA,
Argentina, Chile, Mexico, Taiwan, Hungary, Finland and others. The
toxicity of arsenic compounds in groundwater/soil environment depends
largely on its form (organic or inorganic), and if in inorganic forms,
then on its redox status and pH. Thus, the arsenites are much more
soluble, mobile and toxic than arsenates in aquatic and soil
environments.
High arsenic concentration in groundwater is generally associated with
the geochemical environments of volcanic deposits, geothermal systems
and basin-fill deposits of alluvial lacustrine origin. As regards the
widespread arsenic contamination in groundwater in parts of West Bengal
(India) and Bangladesh, confined within the delta bound by the rivers
Bhagirathi and Ganga-Padma, two major hypotheses, both of geogenic
origin, have been proposed. These are the pyrite oxidation hypothesis
and the oxyhydroxide reduction hypothesis. The latter seems to be more
consistent with the experimental observations on the nature of the
aquifer in the affected delta.
The main focus of attention of such arsenic contamination in the Bengal
delta basin, until recently, has been exclusively on such contamination
in groundwater derived drinking water. It is only rather recently that
the agricultural sector, which receives the major share of such
contaminated groundwater as irrigation source, has received attention
for quantifying the influence of the said toxin (i.e., arsenic) on the
soil-crop-animal continuum. Indeed, this Viswavidyalaya led, for the
first time, an inter-disciplinary, inter-institutional study, initially
funded by the Indian Council of Agricultural Research (and subsequently
by the State and Central Governments), characterizing the aforesaid
effect of arsenic on soil-crop-animal system. These findings have aptly
demonstrated the pathways, other than drinking water, through which
arsenic may have access to human food-web.
A large number of important results have accumulated from such
studies, not only on the characterization of the entire gamut of
intricacies of arsenic contamination spectrum in the said continuum,
but also on a number of effective remedial measures to contain the
toxic effect of arsenic. In particular, the surface water bodies,
located in the affected belt, have remained largely free of arsenic.
This tends to suggest that the soil, which receives arsenic
contaminated irrigation water, acts as an effective sink to contain the
toxin, thereby preventing the surface run-off to carry it to the
adjoining water bodies. The retention of arsenic by the soil organic
fraction and the incorporated organics in the affected sites of study
has been amply demonstrated, so also the release potential of arsenic
from the resulting organo-arsenic complexes by the competing oxyanions
such as phosphate and nitrate. Furthermore, the effective retention of
arsenic by the soil colloidal fraction was shown to be essentially a
ligand-exchange phenomenon, influencing the surface charge
characteristics of the given soils. The latter may have far-reaching
consequences on the appropriate management interventions.
The application of FYM and phosphate was found to have opposing effect
on release of native and applied arsenic in the contaminated soils,
with FYM reducing such release, thereby tending to moderate the toxic
effect of arsenic in soil-plant system. This agreed well with the
findings of a supporting pot-culture experiment, raising rice, which is
particularly susceptible to arsenic toxicity.
Indeed different crop plants raised in a crop cafeteria experiment
exhibited varying tendencies to accumulate arsenic. Such accumulation
in different plant parts also tended to fall off in the following
sequence: root > stem > leaf > economic produce. Moreover,
inclusion of pluses/other legumes / green manure crops in the cropping
sequences, coupled with organic manure addition, was found helpful in
moderating arsenic build-up in soil and plant parts.
Field studies, examining lowland rice (boro paddy), revealed that the
extractable arsenic in soil and also the plant loading of arsenic was
drastically reduced by zinc application to soil in which this
micronutrient was marginal to deficient. The grain yield of summer
(boro) rice in such studies was also found not to vary significantly
between the treatments of continuous ponding and judicious intermittent
ponding; however, the latter saved the contaminated irrigation (ground)
water, thereby bringing less of the toxin to the soil/crop system.
The arsenic decontaminating ability of the microorganisms, prevalent in
the contaminated soils, was also monitored. This led to the
identification of two genera of blue-green algae (BGA) (namely,
Anabaena sp. and Nostoc sp.), and four different types of bacteria
showing promise of arsenic decontamination ability. Furthermore,
several weed species, growing in the wild in the affected areas of
study, namely Ludwigia parviflora, Lantana camara, Eleusine indica,
Filmbristylis sp., etc. also showed promise of accumulating
considerable amounts of arsenic in their vegetative biomass. The latter
could be of importance in regard to cost-effective phytoremediation
options for the given arsenic contamination problem.
An important point to note here is that as one passes from the
contaminated groundwater to crop plants via soil, the arsenic
concentration gets gradually built up, leading to its magnification.
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ALTERNATE LAND USE OPTION: A COMBAT MEASURE TO
REDUCE ARSENIC LOADING IN SOILS OF NADIA DISTRICT, WEST BENGAL
Dipak Sarkar
Principal Scientist and Head
National Bureau of Soil Survey and Land Use Planning (ICAR)
Sector-II, Block-DK, Salt Lake, Kolkata – 700 091
Arsenic (As) - a metalloid ubiquitous in nature and belonging to
groupVB of the periodic table can exist in many oxidation states and
thus can form many inorganic and organic compounds. However, organic
compounds of arsenic are much less toxic than their inorganic
counterparts and the trivalent arsenic (arsenite) are more toxic than
pentavalent state. The clay fraction, amorphous iron & aluminium
oxides and organic carbon have frequently been implicated in sorption
of As by soils. Detailed soil survey conducted recently in
Chakdah block of Nadia district, West Bengal belonging to alluvial
tract of Indo-Gangetic plain (IGP) revealed alarming arsenic
contamination in ground water leading to arsenic pollution in soil crop
environment. Notwithstanding, the seasonal fluctuations the average
arsenic concentration in the ground water was found to be 0.25 mg Asl-1
which far exceed the maximum recommended concentration of 0.1 mg As l-1
of the contaminant with respect to its use both for drinking as well as
for irrigation purposes. Therefore, judicious use of such arsenic
contaminated ground water is the prime need of the hour for which
rationalization of irrigation schedule is supposed to be most
essential. With a view to sustaining the resource quality by way of
reducing arsenic contamination, lifting of lesser quantity of
irrigation water becomes imperative posing greater emphasis for rain
fed rice cultivation along with alternate land use options. Soil-site
suitability evaluation study suggested sesame to be the most suitable
pre-kharif crop after requisite soil-pH correction and potato as
moderately to marginally suitable rabi crop as alternate land use
options having lesser water requirement and thereby can be instrumental
in reducing arsenic contamination in the soils of the area.
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ARSENIC HAZARDS IN WEST BENGAL: CAUSE, EFFECT AND
THE REMEDY
Mitali Sarkar and Sucharita Manna
Department of Chemistry
Kalyani – 741 235
West Bengal, INDIA
University of Kalyani
Arsenic poisoning has become one of the biggest environmental, health
and social disasters of recent days all over the world. The problem is
much serious in West Bengal, where a huge population under nine
districts is badly affected. The average arsenic concentration in
groundwater is found to be 22.5 times of the maximum permissible limit
(0.01 mg/L), set by WHO and at places crosses even 50 times the said
limit. Unfortunately, such a dangerously contaminated groundwater is
the principal source of drinking as well as irrigation water of our
state. A huge region under the kingdom of plants, animals and human
beings is therefore compelled to intake the poison day after day.
Considering the magnitude of this problem, it is very much urgent to
develop an efficient technique for its treatment from aquatic
environment
Researchers have been working to develop possible treatment options of
arsenic contaminated water under laboratory and field conditions. Among
the various techniques available adsorption is proved to be a viable
one. Activated carbon, when used as an adsorbent of arsenic, yields
sufficiently good result, but the cost of treatment is generally very
high. In our present study fly ash, obtained as a waste product from
Thermal Power Plants, is used to remove arsenic from aqueous samples.
The process is found suitable in case of laboratory and real samples.
Although the adsorption efficiency is found low when compared to that
of activated carbon, the waste material can be utilized as a potential
adsorbent considering its cost and easy availability.
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ARSENIC REMOVAL KIT
S. Sukul
B-15/93, Kalyani-741235
W.B., India
A simple, cheap, reliable and reproducible Arsenic Removal Kit has been
developed for 98 % removal of arsenic from arsenic contaminated
drinking water. The kit is in pouch form containing a chemical
composition prepared using charcoal, bentonite powder, sodium chloride,
ferrous sulphate and potassium permanganate. This is a household
preparation, which will save people from arsenic poisoning by providing
safe drinking water.
Key Words: Arsenic Removal Kit, arsenic removal, drinking water.
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