Constructed wetlands....part 5

Eastern narrowmouth toad eggs

Southern toad eggs

The other day I mentioned that the H-02 wetlands were constructed to take help remove copper and zinc from the water leaving an industrial facility before it enters the watershed.  Thought I should discuss the fact that this is not a pollution problem restricted to DOE sites like the Savannah River Site.  Metal contamination is actually a huge problem over a large percentage of the world and copper is a really widespread contaminant.  Like many things, copper and zinc are essential elements and are critical to many of our (and most species') biochemical pathways, but in excess they become toxic.  Copper occurs naturally in the environment but in many places it's concentrations are quite elevated.  Copper is used in the production of many things including kitchen tools, paintings, water pipes, building siding and it's used as a fungicide and algaecide.   As a result it can be really high in water passing through corroding pipes, in all the stormwater runoff from parking lots, roads, and roofs, and from runoff from agricultural areas and mines.  On roads it actually is released from brake abrasion.  In some places it is used very heavily (as copper sulfate) to kill algae in ponds or aquaculture systems or as a pesticide on crops. Unfortunately aquatic environments are always the final receptor of urban wastewater, runoff from mines and agriculture, and industrial effluents--plus some aquatic environments have copper sulfate directly applied to control algae.  It is estimated that 15 million tons of copper are used annually so it's not surprising that many aquatic environments have a lot more copper than would be found there naturally.  As a result, there has been a lot of research on the effect of elevated copper on fish and it can be extremely toxic (and often fatal) to fish.  The EPA has set regulations for how much copper can be allowed in water and in industrial effluent.  The industrial facility on site where the H-02 wetlands exceeded that value and that's the reason the wetlands were constructed---and they do a great job of reducing the copper level to a "natural" level before the water enters Upper Three Runs Creek which runs to the Savannah  River.  Though we know copper is highly toxic to fish there is a lot less known about it's effect on amphibians and that's what we've been studying and will talk about next.  Two of the species we've studied are Southern toads and Eastern narrowmouth toads and their eggs are shown in the photos.