About 6 months ago I wrote a post reporting on decreasing nitrate concentrations in Danish groundwater. The other day I ran across some encouraging news from a study in Germany, on organic pollutants in rivers.

A large-scale toxicological study was done on four of Germany’s largest rivers, the Elbe, Ems, Weser, and Aller. [Occurrence and Toxicity of 331 Organic Pollutants in Large Rivers of North Germany over a Decade (1994 to 2004), by R.B. Schäfer et al., Env. Sci. Tech. 45(14):6167–6174. You may need a subscription to access.]

The Elbe is one of the most polluted rivers in Germany. The researchers analyzed for 331 organic compounds over a 10 year period (1994-2004). The bad news is they found 257 of those compounds, and 24 were found in more than 40% of the samples. Some of the most commonly detected were polyaromatic hydrocarbons (e.g., fluroanthene, pyrene, phenathrene), pesticides and their breakdown products (e.g., hexachlorocyclohexanes and one of Illinois’ favorites, atrazine), and halogenated hexanes (e.g., tetrachloroethylene, bromoform, carbon tetrachloride). Bad stuff, and they can be acutely toxic to aquatic organisms.

The good news is that several chemical groups showed significant declines in detection frequency at all sampling sites. These included pesticides and halogenated alkanes and several others.

While nobody should be happy at the number of toxic chemicals in the world’s rivers, it is encouraging that policies, regulations, and actions undertaken to reduce pollution apparently are working. It was just a few decades ago in this country that rivers like the Cuyahoga in Cleveland and Lake Erie were severely polluted, and today their quality is much improved.

Here’s the link to my earlier post on nitrate in Denmark’s groundwater.