In the face of current environmental challenges, a previous victory in evidence-based policy is worth revisiting. In north-eastern Ontario Canada, long term collaborative science described the widespread acidification of lakes and identified the source. That knowledge, translated into policy, is now resulting in ecological recovery.
For someone from a dry continent, north-eastern Ontario is impressive. The somewhat flat landscape is dotted with thousands of lakes large and small. While exploring these lakes by canoe (highly recommended) its easy to forget how extensively they have been altered by modern industrial man.
The region is rich in nickel deposits as well as lakes and nickel mining has been a major part of the economy for decades. Unfortunately, smelting of ore releases sulphur into the atmosphere. When sulphur combines with water vapour, sulphuric acid is produced.
By the 1980s, an estimated 19 000 lakes in Ontario had been affected by acid deposition. Over 7000 lakes around the town of Sudbury alone were acidified to the point that biological damage occurred.* The lakes closest to the Sudbury smelters were also highly metal-contaminated.
During this time knowledge was being generated through a range of scientific approaches. In addition to ongoing monitoring of water and biota, paleolimnological reconstructions were done to see what had lived in lakes prior to acid rain. Controlled laboratory and field toxicity tests, and lake-scale experimental liming studies were also done to test the effects of acidification.
The body of scientific knowledge showed that widespread lake acidification was directly due to excessive acid deposition, that lake acidification had caused extensive damage to lake communities, and that removal of acid stress would stimulate the chemical and biological recovery of aquatic ecosystems.
In Canada and the USA policies were enacted to deal with the cause of the problem. This took the form of control programs put in place by government agencies to reduce acid emissions.
By 2003 total North American emissions were about 40% less than in 1980. Large-scale emission reduction programs implemented at the Sudbury smelters in the 1970s and 1990s, achieved overall reductions of ~90% in sulphur and metal emissions in comparison with the peak emission levels in the 1960s.
Ongoing monitoring has shown these emission reductions have resulted in water quality improvements. There is also evidence of biological recovery for many aquatic organisms, including phytoplankton, zooplankton, benthic invertebrates, and fish.
While acidity can be lessened, other chemical inbalances can remain. Calcium for example has been depleted over years of leaching from lake watersheds. Unfortunately it plays an important role in aquatic ecosystems. Many aquatic organisms require calcium to live and it also modifies how they are affected by a variety of stressors such as metals and ultraviolet radiation.
This Canadian example resonates with me in several ways. It illustrates how an integrated science effort can help solve complex environmental problems. How, given incentives, industry can change practice and continue operation. And also how major ecological damage is rarely fully reversible. All seem pertinent for Australia.
The full article on which this post is based is: Limnology in northeastern Ontario: from acidification to multiple stressors by W. (Bill) Keller Canadian Journal of Fisheries & Aquatic Sciences, 2009, 66, 1189–1198.