Mark and I have been working with the Iron industry to try to understand the effects of iron on aquatic ecosystems. We have been analysing extensive field monitoring data on the quality of invertebrate communities in rivers and relating this to the levels of different forms of iron (total, dissolved, or particulate) that are present. Invertebrate communities do appear to be adversely affected when high levels of iron are present. This represents a possible approach towards deriving Environmental Quality Standards which are directly related to existing measures of ecological quality, therefore providing a better link between chemical and ecological quality in surface waters. It also avoids the need for laboratory test data, which can be especially difficult to interpret in the case of iron due to its precipitation behaviour. Some of the results of this work have recently been published in the Bulletin of Environmental Contamination and Toxicology (abstract).