Arsenic at Faridpur in Bangladesh

ARSENIC WITH PEOPLE’S INTEREST

Arsenic is an element that has attracted people’s interest since ancient times. Public opinion used to consider it a powerful poison, and it is in the news again now as a result of the biggest arsenic calamity in the world, reported in Asian areas. This has led to a rediscovery of arsenic by the public, despite the fact that it has always existed in the environment as a “silent” toxin in numerous regions in the world. Every year, new areas are detected in which the presence of arsenic exceeds the levels considered normal by international organizations.

Since the discovery of arsenic contamination in West Bengal there has been apprehension about arsenic contamination in Bangladesh groundwater as well, particularly in the western border districts. The Department of Public Health Engineering (DPHE) made the first discovery by testing a few wells from Baragharia mauza of Nawabganj in 1993. (Kazi Matinuddin Ahmed, banglapedia)

As 2006, the First International Congress on Arsenic in the Environment, was held in Mexico City in 2006, focusing on “Natural Arsenic in Ground waters of Latin America”. Hence the present announcement of the Second International Congress, As 2008, with the title “Arsenic from Nature to Humans”, which will be held in Valencia (Spain) from 21 to 23 May 2008.

OBJECTIVE

This project was done on the basis of three major objectives. This are-

1.    To determine the level of Arsenic (As) concentration in some specified biological components belongs to different categories and to investigate whether the concentration is in toxic level or not.

2.    To identify the possible impacts of As contamination upon these components as well as on bio diversity.

3.    To draw a cycle of As contamination along these components.

STUDY AREA AND LOCATION

The sadar upazilla of Faridpur district was purposively selected for my research study. The upazilla belongs to low Ganges river floodplain. It is located between 23°29´ and 23°44´ north latitude; and between 89°41´ and 89°´56´ longitude. The upazilla occupies an area of 396 sq.km. Including 16 sq.km. reverine landscape. There are 11 unions of this upazilla. The population of this upazilla is 0.28 million.

SITE SELECTION

A discussion meeting was held with my co-supervisor Mr. Tarikul Alam before going to select sampling sites. As he was involved with his own project in Machchar union with arsenic experiment and he is well known about the geographical condition of that site so I have chosen this union for my sampling site. My whole sampling was conducted at Poranpur (Koarpar) village under the Poranpur block of Machchar union.

WHAT IS ARSENIC?

Arsenic is a naturally occurring element widely distributed in the earth’s crust. In the environment, arsenic is combined with oxygen, chlorine, and sulfur to form inorganic arsenic Compounds. Arsenic in animals and plants combines with carbon and hydrogen to form organic arsenic compounds. (ATSDR Aug, 2007).

Name: arsenic                         

Symbol: As

Atomic number: 33

Atomic weight: 74.92160 (2)

Standard state: solid at 298 K

Colour: metallic grey

Classification: Semi-metallic

Group number: 15

Group name: Pnictogen

Period number: 4

Block: p-block.

Notes:

■ Inorganic arsenic is about hundred times more toxic than organic arsenic.

■ Arsenic (III) is about sixty times more toxic than Arsenic (V).

ARSENIC IN THE ENVIRONMENT

Arsenic is present in all soils. The arsenic content in virgin soils is 0.1 to 40 mg/kg and average is about 5 to 6 mg/kg, but varies considerably among geographic regions. Soils overlying with sulfide on deposits contain arsenic at several hundred mg/kg and reported maximum 8000 mg/kg. The natural level of arsenic in sediments is usually below 10 mg/kg and varies considerably all over the world. The arsenic in air is less then 0.01 µg/m³.

Arsenic is found at low concentration in virtually all natural waters. The maximal permissible concentration in drinking water is 50µg/L and recommended value is 10µg/L by EPA and WHO. The above values are on total arsenic without compound specific. The sea water ordinarily contains 0.001 to 0.008 mg/L of arsenic. The ratio of As (V) and As (III) is 0.1:1 to 10:1. In ground water, ordinarily found that about 50% present As (III). Although normally ground water does not contain MMAA and DMAA, but surface water contain all the species of arsenic.

WHAT IS BIO DIVERSITY?

Biodiversity has been most generally defined as the "full variety of life on Earth" (Takacs, 1996). More specifically, biodiversity is the study of the processes that create and maintain variation. It is concerned with the variety of individuals within populations, the diversity of species within communities, and the range of ecological roles within ecosystems (Graham Bell, pers. comm.).