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SESSION 5: Short contributions and discussion

SESSION 5: Short contributions and discussion

(1) Geochemistry and speciation of solid and aqueous phase arsenic in the Bengal Delta Plain aquifers

Presentation

Bibhash Nath, Postdoctoral Researcher, Department of Earth Sciences, National Cheng Kung University, Taiwan

Debashis Chatterjee, Associate Professor, Department of Chemistry, Kalyani University, India

Jiin-Shuh Jean, Professor, Department of Earth Sciences, National Cheng Kung University, Taiwan

Prosun Bhattacharya, Associate Professor, Department of Land and Water Resources Engineering, Royal Institute of Technology, Sweden

Kazi Matin Ahmed, Professor, Department of Geology, University of Dhaka, Dhaka 1000, Bangladesh

bibhash12@yahoo.com

The groundwater chemistry of Bengal Delta Plain (BDP) is mostly alike for shallow aquifers, however, depends largely on the geospatial signatures, sediment texture and mineralogy. The major pathway of high arsenic (As) concentration in groundwater is the reductive dissolution of the "As-traps" (mostly sedimentary iron-oxides and hydroxides) under local reducing condition. The high As aquifers are largely in the low land areas intersparsed with low arsenic zones. The release of redox sensitive species (As, Fe, Mn) is the function of bioavailable forms of iron oxide, concentration as well as distribution of organic matter and availability of electron donors in the alluvium. Aqueous speciation indicate that the ratio of As(III)/(V) is varying with varied combination of As(III)/Astot over a large geographical area of BDP. Water chemistry reveals that siderite and vivianite are commonly in supersaturated stage (insoluble phases) in the groundwater, that further confirms by solid phase chemical partitioning. The concentration and distribution of siderite/vivianite is also important in explaining large-scale and variable aqueous As species in groundwater. Solid phase chemical partitioning shows that the arsenic is associated with amorphous Fe-oxide together with surface bound PO43- in coarser sediments and is playing an important role in As mobilization.

Those who wish to discuss these issues further - please feel free to contact Bibhash Nath at bibhash12@yahoo.com

(2) The mobilization of arsenic in groundwater and arseniasis from the Hetao Area, Inner Mongolia

H. Zhang

School of Environmental Science and Engineering, Shanghai Jiaotong University, 800 Dongchuan Rd., Shanghai 200240, P.R. China. Tel: +86-21-54748942, Fax: +86-21-54740825, e-mail: huizhang@sjtu.edu.cn

In Hetao Area, Inner Mongolia, China, Quarternary alluvial aquifers used for public water supply are contaminated by naturally occurring arsenic, which is heavily affecting the health of the 180,000 people there. A lot of efforts to improve drink water have been carried out since 1990s. But the arsenic effects for resident health cannot be avoided effectively. This indicates that the cognition, which the arsenic is derived from rich arsenic aquifers formed under the anoxic conditions, for arsenic contamination in the groundwater in Hetao Area may not be right. Our study shows that the contaminant derives from the upper reaches where groundwater is high in arsenic. The concentration of As in the water reduces from 0.251 ml/L to 0.005 ml/L along the working line by 44 km. Arsenic concentration in the soil varies gradually at the working lines along the flow direction as follows: from 22.0 mg/kg to 9.6 mg/kg, from 20.0 mg/kg to 7.9 mg/kg', and from 18.0 mg/kg to 9.9 mg/kg at work lines by 52, 68, and 40 km respectively. Strontium isotope data of well water, which is used for drinking by residents, and the variation of arsenic levels in resident people hair suggest that mobilization of the arsenic from the upper reaches, front Yin Mountains, to the alluvial aquifers of the lower reaches may be responsible for the current health crisis of resident arseniasis. Potential solutions should be: the treatment of mining water before drainage in upper reaches, finding groundwater in too depth to be reached by rich arsenic water from mining and weathering in upper reaches or the groundwater under aquifuge stratum, and treatment of groundwater as drinking water at the point of use or in the water supply plant.

Key Words: Arsenic poisoning; Groundwater; The Hetao Area, Inner Mongolia

(3) Vulnerability of population exposed to arsenic contamination in the Mid Ganga Plain of Bihar, India

Presentation

Dr. Ashok Kumar Ghosh, Prof.-in-Charge, Dept. of Environment and Water Management A.N.College, Patna

Dr. Nupur Bose, Lecturer, Dept. of Geography, A.N.College, Patna, India

nupur.bose@gmail.com

Dr. Narendra Kumar Roy, Resource Person, Dept. of Environment and Water Management A.N.College, Patna, Bihar

Dr. Ajay Upadhyay, Resource Person, Dept. of Environment and Water Management A.N.College, Patna, India

Mr. Amardeep Singh, Research Scholar, Dept. of Environment and Water Management A.N.College, Patna, India

Mr. Sushant Kumar Singh, Research Scholar, Dept. of Environment and Water Management A.N.College, Patna, India

Arsenic contaminated aquifers, being used for direct and indirect human consumption, have severe health implications among the rural population in the state on Bihar, India. This study covered a 10 km. belt along the Ganga river in the four districts of Bhojpur, Patna, Vaishali and Bhagalpur. The purpose of this research was to obtain the distribution and quantum of human population at risk of arsenic poisoning and population composition characteristics of the arsenic-affected belt. The methodology adopted was based upon self-generated and confirmed primary data on abnormally high arsenic concentration in ground water ranging from above 10 ppb. to 1861 ppb. Percentage of hand pumps testing with more than 10 ppb. arsenic content were calculated. This data was compared with the Census 2001 data to obtain estimates of affected population, while Topographical and Administrative Block Maps of all four districts were referred to for studying the spatial pattern of this population. The result showed that approximately 1,537,426 persons [about 47% of the population] residing in the study belt are at risk. In Bhagalpur study belt, the vulnerability extends to more than 75% of the population. Symptoms of arsenic poisoning are widespread, especially among child population. Appropriate mitigation strategies are yet to be undertaken in this study area.

(4) Occurrence and Health Effects of Arsenic in China

Zheng, Y.1,2, D.-J. Sun3, G.-F. Sun4, G.-Q. Yu3, S-X. Wang5, A.-H. Zhang6, D. An7, D.-S. Li7 and O. Odediran8

yan.zheng@qc.cuny.edu

1 Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA

2 Queens College, City University of New York, Flushing, NY 11367, USA

3 The Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention, Harbin Medical University, Harbin, Heilongjiang 150081, P.R.China.

4 Department of Environmental and Occupational Health, College of Public Health, China Medical University, Shenyang, Liaoning, PR China

5 Shanxi Institute for Prevention and Treatment of Endemic Disease, Linfen, Shanxi 041000, China

6 Department of Toxicology, School of Public Health, Guiyang Medical University, Guizhou, 550004, PR China

7 Guizhou Center for Disease Control and Prevention, 73 Bageyan Road, Guiyang 550004, Guizhou, China

8 UNICEF, Water and Environment, New York, USA

Presentation

China has well-documented As endemics areas with high occurrence rates of arsenicosis possibly due to longer histories of exposure and biomedical investigations dating back to the1980s. Recently, five articles that report the health effects of As in the exposed population and describe the mitigation approach used to reduce As has appeared as a mini-monograph in Environmental Health Perspective. In a survey of 135,492 individuals in eight provinces, 10,096 cases of arsenicosis with various degrees of skin lesions were identified. This arsenicosis occurrence rate of 7.5% is likely an overestimate because the survey focused more on known and suspected endemic areas of arsenicosis. However, it is worth noting that the percentage of arsenicosis cases correlates positively with the percentage of wells containing > 50 μg/L of As (R2 = 0.70). For example, if a province had on average 10% of wells containing > 50 μg/L of As, then the occurrence rate of arsenicosis is also ~ 10%. In Inner Mongolia, a comparison of urinary As metabolites in children and adults showed that children had a higher percentage of dimethylarsenic acid (DMA) than adults. In Shanxi, an ecological study of 720 children between 8 to 12 years of age showed that IQ scores decreased from 105 ± 15 for the control group, to 101 ± 16 for the medium-As group with 142 ± 106 μg/L (p < 0.05), and to 95 ± 17 for the high-As group with 190 ± 183 μg/L (p < 0.01). In Guizhou, a population exposed to mg level of As originated from coal-fired stoves showed that long-term As exposure may be associated with damage of chromosomes and DNA, gene mutations, gene deletions, and alterations of DNA synthesis and repair ability. Fortunately, health education to that population has resulted in dramatic decrease of exposure, reflected in reduction of urinary As concentrations by a factor of 4.

A strong associate between As and Au-deposits in China have been noted. This association is used to illustrate the heterogeneous nature of As distribution in the crust and to shed light on the tectonic environment that lead to anomalies of As concentrations in source rock. Further geochemical investigations are much needed to understand the heterogeneity of As distribution in the crust, and its significance on occurrence of elevated groundwater As in sedimentary aquifers. However, the systematic geographic distribution of As-rich minerals in Au deposits along the orogeny belts was suggestive that As anomalies in whole rock may be more wide spread, the geographic extent of such As anomalies in whole rock remain to be defined by more whole rock analyses. The distribution of As in soil from on-going high density sampling in China can be used to identify promising areas for whole rock analyses. An intriguing prediction of the conceptual model of As distribution in the crust is that rifting and pull apart sedimentary basins in China are more prone to have groundwater As problems if they are down gradient from high As source rocks.

(5) "Mass Arsenic Poisoning of Rural Bangladesh - Health impact and Community based mitigation of patient management and Safe Drinking water, DCH Experience."

Mahmuder Rahman, Quazi Quamruzzaman, Jabed Yousuf, Golam Mostofa, Altab Elahi, Afroza Khatun, Sharmina Banu and Ronjit Halder

Prof. Mahmuder Rahman
Trust Co-Ordinator-DCHT
Dhaka Community Hospital
190/1 Bara Moghbazar, Wireless Railgate
Dhaka - 1217
Bangladesh
dch@bangla.net

Presentation

Bangladesh is facing a massive health and environment problem along with other South and South-East Asia countries caused by groundwater arsenic contamination.

Millions of populations are affected. Thousands are now suffering from cancers, gangrene and other serious health, social and environmental problem from arsenic poisoning.

In June 1996, Dhaka Community Hospital detected arsenic Patient in Paksey, Pabna district and pioneered the detection of Arsenic Contamination of drinking water and Arsenic health effects in rural Bangladesh. Dhaka Community Hospital conducted a limited field survey with School of Environment Studies (SOES) of Jadavpur University, India and published its findings in a National conference in January 1997 and established the evidence of mass arsenic poisoning of rural Bangladesh. Since then DCH conducted survey all over Bangladesh with various national, International and UN agencies and organised 6 international conferences. DCH was instrumental in mobilizing national and international interest and activities to counter these devastating health and environmental hazard facing millions of people in South and South-East Asia.

Pathophysiology of "Arsenicosis", the term coined to define the disease manifested by chronic arsenic poisoning and its complications are still not clear to the medical profession. Researches have been initiated and lot more will be necessary in future to understand the nature of these disorders.

Dhaka Community Hospital has initiated a program of community based Arsenic Mitigation of Patient management and Safe Drinking water in rural Bangladesh. This programme is being reflected in National Arsenic Mitigation Policy and Action Plan and various organizations has taken up this model of Arsenic mitigation programme and are being implemented.

(6) The distribution of arsenic in groundwater in five states of India and geochemical data from an arsenic-affected area of Ballia District, Uttar Pradesh

Presentation

Ross Nickson, UNICEF Kolkata, India

Dr. Nalini Sankararamakrishnan, Indian Institute of Technology, Kanpur, India

Testing of groundwater used for drinking for arsenic has been undertaken more widely by state governments in several states of India in recent years with the support of UNICEF. Available data for five states are discussed and this provides the most up-to-date picture of areas known to be affected by arsenic in groundwater in the Indian portion of the Ganges-Brahmaputra river basin. In West Bengal, water from 132,262 government installed handpumps in 8 districts has been tested and overall 25.5% of samples were found to contain arsenic at concentrations greater than 50 µgl-1 and 57.9% at concentrations greater than 10 µgl-1. On the banks of the Brahmaputra in Assam, to date, samples from 5,729 government handpump sources in 22 districts have been tested for arsenic. Overall, samples from 6.3% of sources were found to contain arsenic at concentrations greater than 50 µgl-1 and 26.4% at concentrations greater than 10 µgl-1. In Bihar, on the River Ganges upstream of West Bengal, 66,623 sources from 11 districts have been tested and water samples from 10.8% of sources were found to contain arsenic at concentrations greater than 50 µgl-1 and 28.9% at concentrations greater than 10 µgl-1. Upstream of Bihar in Uttar Pradesh, to date water samples from 103,578 government installed handpump sources have been tested. 1.3% of the samples tested were found to contain arsenic at concentrations greater than 50 µgl-1 and 8.6% at concentrations greater than 10 µgl-1. Finally in one district of Jharkhand, lying on the Ganges alluvial plain between Bihar and West Bengal, 9,007 sources have been tested and water samples from 3.7% of sources were found to contain arsenic at concentrations greater than 50 µgl-1 and 7.5% at concentrations greater than 10 µgl-1. In West Bengal all public sources were tested in areas known to be affected by arsenic so these figures are representative of the situation in 79 arsenic-affected blocks in 8 districts, not for the state as a whole. In Bihar, Uttar Pradesh, Jharkhand and Assam testing was focused on blocks adjacent to the river Ganges or Brahmaputra so again the percentage calculations are only representative of the specific areas tested and not the state as a whole. Testing is ongoing in several states and the complete picture is yet to emerge in some areas. Arsenic in groundwater is also known to occur in the state of Chattisgarh in a different geological setting to the alluvial plains of Northern India. This occurrence of arsenic is not covered here. Data on the geochemistry of arsenic-affected groundwater in Ballia District in Eastern Uttar Pradesh will also be presented. The data indicate that the groundwater is generally less reducing in nature than further downstream in the Ganges/Brahmaputra delta areas of West Bengal/Bangladesh and As(V) is present in appreciable concentrations. This has implications for arsenic testing and implementation of arsenic treatment technologies.

Ross Nickson
Water Quality Specialist
United Nations Children's Fund
219/2 A.J.C. Bose Road
Kolkata 700 017, India
rnickson@unicef.org