Ganga Action Plan
WQ1
WQ2
WQ3
Factor X
The Special Properties of the Ganges Water |
Background Information |
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Given the difficulty and expense associated with wastewater treatment it is important to determine the maximum level of contamination that can safely be discharged to a river. With a goal of cleaning the Ganges, the Ganga Action Plan (follow this link for details on this initiative) defined requirements for treatment, relying heavily on western technology (follow this link for a more detailed discussion and a laboratory activity associated with wastewater treatment). The broadcast presented above suggests that Ganga may not behave like other rivers and that more study and discussion is needed before an effective treatment strategy can be developed. If untreated sewage is being dumped into the river at locations above the bathing festivals why is there no evidence of disease outbreaks? Three answers suggest themselves: the diseases are being poorly reported, the bacteria in the river do not survive long enough to have an effect on human health, or the bathers have developed a tolerance to the organisms they encounter. Some combination of the three is certainly also possible. |
Discussion and Research Questions 1. What are the challenges faced by governments trying to understand the consequences of people's use of a possibly contaminated river? Given the probability that Ganga's waters contain pathogens, including bacteria, viruses and protists, and toxic materials including toxic organic compounds and heavy metals. Prepare a table describing the probably human health effects of these materials. 2. Using the four steps of risk assessment, describe how a health organization could determine if the river was adversely affecting the health of the target populations. 3. How might scientists explain the results if the analysis suggested that few of the expected effects were evident in those exposed? How might the discharge of pollutants into a river occur with few problems? Would you feel it was safe to use the waters if this "no effect" outcome were found to be true? Why or why not? 4. How might bacteriophage populations reduce the levels of bacteria in the receiving waters? Are the suspected fluctuations in these populations consistent with the principles of population dynamics developed to describe predator-prey relationships? 1) What water pollutants are likely to play a significant part in the spread of water-borne illness? 2) What are the primary sources of these pollutants associated with both direct and indirect discharges to the river? 3) How can a River clean itself? |
• Bacteria and viruses; diseases spread in this manner include cholera
Question 2: Pollutants reach a river either from point sources, flowing out of an identifiable discharge point, or non-point, flowing over land and entering the river from a variety of locations. Point sources include waste water treatment plants and industrial discharges, non-point sources include runoff from agricultural activities or runoff from streets and buildings in developed areas.
Question 3: As discussed above, a river can clean itself. In the United States and Europe the introduction of legislation reducing the inputs of pollutants into a river has led to dramatic improvements in the quality of the Nation's waters. More subtle and complex processes may also play a role in this. Why do apparently few Indians suffer from the adverse effects of exposure to the wide assortment of pollutants which occur in the river? This is a difficult question to answer, made unclear by the lack of good information on the extent of water-borne illness along the river and the difficulty associated with identifying specific causes and effects for many common health problems. If the incidence of water-borne disease is indeed low despite the tremendous exposure, one explanation is the development of a tolerance to the pollutants among the affected populations. Certainly a visitor to any country runs a risk of digestive problems associated with the ingestion of a new and unfamiliar group of pathogens. There may be differences in behaviors; native peoples may have developed strategies to reduce the ingestion of the disease causing organisms or in removing them after exposure. As discussed in the broadcast, there is evidence to suggest that although the bacteria most closely linked to many of the most severe water-borne diseases occur in large numbers in Ganga, these bacteria are short-lived because of the activity of bacteriophages, viruses that specifically target the bacteria and reduce their numbers so quickly that they have little opportunity to infect the population. Persisting in a resting state during times when bacterial populations are low, the virus populations explode immediately upon the appearance of large numbers of bacteria, associated perhaps with a festival or a failure of a sewage treatment facility. |
Further Resources |