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Name: Andy
Status: Student
Grade: 9-12
Location: OK
Country: United States
Date: May 2006

In a wetland, what would a high level of chloride mean in a pond?
In earth science class we did a lab and I tested for chloride. The level was the highest on the card, and I was just wondering if it could be hazardous or if it helped to cleanse the water.

It is difficult to generalize what impact elevated levels of chloride would have on a wetland or pond. Some species of plants and animals tolerate high levels of chloride quite well. Others do not. Some ponds and wetlands are "naturally" salty because they are near an ocean. It also depends upon what the cation associated with the chloride is. Sodium would have a different impact than calcium, for example.

The way to determine the effect of high chloride levels would be to conduct an inventory of the plants and aquatic animals in the test pond and compare that distribution of plant and animal population from a similar pond that has a low level of chloride. Such studies aren't easy because effects may be delayed and the chloride level may vary. For example, if the source of the chloride was runoff from salting a nearby highway. The elevated chloride may only last a matter of days and its effects might be minimal. On the other hand, if the source of chloride is constant, one could see very different effects.

Vince Calder

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