Elevated level of arsenic in groundwater of India and Bangladesh should be termed as "contamination" or "pollution" ? Please give reasons to support your answer.
Elevated contents of arsenic in the ground- and surface water in India and Bangladesh are first and foremost the result of a geogen process caused by oscillating redox conditions in one of the strongest tidal regimes on the globe the impact of which can be recognized for quite a long distance landward of the coastline. Contamination which is synonymous with pollution refers to each and every process be it anthropogenic or geogen making water undrinkable or unusable for all kinds of living beings by the addition of chemical substances and/ or changing the physical regime.
H.G.Dill
I thinking its belong the soluble some rocks during surface water to the groundwater
Harald G. Dill explains the reasons to your question explicitly and I totally agree with him
Avinash Ranjan
According to the Agency for Toxic Substances and Disease Registry (https://www.atsdr.cdc.gov/phs/phs.asp?id=18&tid=3), the natural levels of arsenic in soils range from 1 to 40 mg/kg with an average of 3-4 mg/kg. For natural surface and groundwater, the average arsenic concentration is generally about 1 part in a billion parts of water (1 ppb). Beyond this normal range regardless of the causes (geogenic or anthropogenic), it is considered as contamination or pollution.
What is the difference between contamination and pollution? Can the both be used interchangeably?
There is a practical benefit of separating contamination (can be both by humans and nature) and pollution (only by humans). In forensic they say a crime scene is contaminated if somebody changed it, but it is not polluted unless somebody added something.
The primary reason for the elevated concentration of As(III) in groundwater is subsurface geogenic processes. The interactions between arsenic bearing rocks and groundwater cause weathering/dissolution of these rocks via redox processes, and introduce As (III) in the groundwater. However, surface water may be contaminated by anthropogenic activities and further entering in shallow aquifers. Thus, arsenic in water is introduced by both anthropogenic and geogenic processes. Therefore, it is better to say arsenic contamination rather than pollution. Practically, it does not make much difference. Furthermore, surface water containing organic matter may be inducted in shallow and deep aquifers which may enhance the dissolution of arsenic bearing rocks induced by microorganisms, resulting in a rapid increase in As level.
Arsenic in the groundwater can come from leaching out of the bedrock, is fairly common and would be considered "contamination." Arsenic is used as pesticides (spread around to kill rodents), fungicides (sprayed on fruit trees), in industry, as wood treatment for pests, etc. With rain, the runoff containing the arsenic would be considered "pollution."
Arsenic level increasing due to leaching from earth surface and rocks. That are arsening increase naturally not due to artificial contaminants or artificial chemicals.
It is the concentration of As in the host minerals which is Fe sulfide the most common sulfide ("Jack of all trades") and the oscillating redox conditions in the host environment, all of which are natural.
H.G.Dill
The Contaminant is the substance that was introduced by man into the environment by any means while the pollutant may be induced by man or may be present in the natural environment.
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MEDTOX TEXTBOOK: TOXICITY OF HEAVY METALS AND RELATED COMPOUNDS: Chapter 67; ORDOG
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If you are measuring arsenic, I should say this I found to be of most importance after 40 years of being a practicing Medical Toxicologist. When you ask for an arsenic level, make sure that you also ask to have the result fractionated. Obviously, you only need it if it is high, but then to fractionate it you need to run the test again, extra money. So specify, if the level is elevated, please fractionate it, on the requisition sheet. As an example, the police come to me with a high arsenic level and want to know if it is homicide; you have to do the test again and fractionate it. It may come back that it is all organic arsenic, from the lobster dinner the guy had the night before, and not homicide. Also, I provide our chapter you your review.
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