I happened upon this gem last night. It is an episode of the PBS news magazine Frontline. It is a summary of what problems face our waters today. Primary examples of current threats include nutrients, endocrine disruptors, and PCBs.
Nutrients largely enter our waters from wastewater discharge and stormwater runoff contaminated with fertilizer and agricultural byproducts. However, combustion byproducts found in automobile emissions also contain nutrients and find their way into open water in significant amounts. These nutrients cause an explosion of microbial growth, which can reduce dissolved oxygen and kill everything that depends on it in the water, such as fish. In fact, the problem has gotten so bad that oceanic dead zones have spread across the world. One of the most famous occurs in the Gulf of Mexico around the Mississippi River delta. It is in order to stop these occurrences that stormwater best management practices (BMPs) are required as part of most urban development, but agriculture is still largely unregulated.
Endocrine disruptors are chemicals that mimic hormones in the body. They are used for this reason in drugs to treat certain conditions. It also happens to be that certain industrial products happen to have this property. A good example is bisphenol a (BPA), which is found in various plastics. It happens to be used in many drink containers and, for this reason, public pressure has forced many baby bottle makers to go BPA-free. The fear in this case is that boys will be femenized, possibly to the point of having fertility problems. When endocrine disruptors make it into the wild, it has been known to make organisms that are genetically of one sex to develop as the other. As far as I know, there is no current regulation of endocrine disruptors in our water (drinking, waste, or natural).
Polychlorinated biphenyls (PCBs) are an example of a kind of toxic and possibly carcinogenic chemical that is also very persistent as they do not readily degrade. PCBs are usually associated with old electrical facilities. Because they are so persistent, PCBs can accumulate over time in animals from both what they eat and their surroundings. Exposure can get worse from generation to generation as the PCBs can be passed from mother to baby. The effect is that an entire population could potentially be killed by PCBs. I have actually had the occasion to work on the design of road crossings of a stream contaminated by PCBs. It was necessary to span the stream so as not to disturb it and potentially release any PCBs that might be contained in the soils and sediment. The site has been designated a superfund site, though no cleanup has yet occurred.
If you watch the following video, it will take you through the history and the process by which Chesapeake Bay, Puget Sound, and other waters have been contaminated. It will also document the effects this has had on the ecosystem and some of the efforts that have been made to mitigate them. One obvious take-home message is: be careful where you fish. Another one might be to be careful what you drink.
Tags: documentary, PBS, pollution, water
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