We have known for a long time that environmental factors have very strong modifying effects on the expression of toxicity, and models will help to both explain this and also aid in remediating contaminated environments by altering the bioavailability of contaminants.

I was pleasantly surprised to learn that my work is highly cited, as I never really looked at the citations. I have tried for at least 10 years to make sure that my papers are submitted to relevant journals with high impact factors, so maybe this has paid off. However, looking at the most-cited papers, I like to think it is the subject matter that is most influential.

What are the circumstances which led you to your work?

My original training was broadly based, which I think helps explain my subsequent success. I first trained at Sheffield University in Geology, Environmental Science, Biology, and Geography, and later majored in Zoology and Botany, finally specializing in plant physiological ecology for my Ph.D. The courses also included a substantial amount of microbiology, which became very useful to me later.

This turned out to be an ideal background for my subsequent career. I am lucky that I work in an organization that, depending on the topic, enables us to work from the fundamental science right through to the more applied levels and interact with users of research. My work has been multidisciplinary and encompasses soil, plant, and microbial systems, and, particularly, the fate and effect of pollutants. More recently we have begun to focus on environmental remediation by looking at either bioremediation or chemical amendments that alter the bioavailability of pollutants. I have also worked on sulphur, but for different reasons. That was because we have cleaned up the atmosphere to such an extent in Western Europe that we have turned a pollutant that was part of the "acid rain" complex into a severe deficiency of what is in fact a major essential nutrient. A key point about the sulphur research is that it has had a high impact on farming and crop quality, but not so much impact on citations.

  Would you describe the significance of this work for your field?

It turns out that the most-cited papers fall into several different categories; perhaps this is a characteristic of multidisciplinary research. For example, work on the impacts of heavy metals on terrestrial systems, which has great implications for environmental protection legislation, is highly cited, as is work on hyperaccumulation of zinc, cadmium, and arsenic in highly specialized plant species. Hyperaccumulators are really the equivalent of the extremophiles that are best known amongst microbial species. Completely new discoveries can readily be made in this area, such as an ecotype of Thlaspi caerulescens that can accumulate 1.4% cadmium in its leaves without damage, and new species of ferns in the genus Pteris that hyperaccumulate arsenic, also to 1% in the leaves. Also of great interest is the work on the transport and localization of metals within the plant tissues, as part of the investigation of the mechanisms responsible for hyperaccumulation. It turns out that many metals are finally accumulated as quite simple salts in large vacuoles in the leaves.

  Where do you see this research going 10 years from now?

In future, I feel that targeted multidisciplinary collaboration can pay off enormously—for example, the work we have started on the molecular mechanisms of cadmium uptake and arsenic accumulation. This area could have practical applications in environmental improvement using green technologies such as phytoremediation. I also feel we are close to constructing models of toxicity of metals in the terrestrial environment that can be used for both risk assessment and environmental protection. We have known for a long time that environmental factors have very strong modifying effects on the expression of toxicity, and models will help to both explain this and also aid in remediating contaminated environments by altering the bioavailability of contaminants.

  What lessons would you draw from your work to share with the next generation of researchers?

You must always focus on something that we do not know about, and take it as far as you can, without repeating what others have done. Also, a couple of my most-cited papers are reviews, but people should realize that you need to have accumulated a lot of research experience before you can write a good review. In the environmental arena we may have to perform 5-10 years of research before putting together a review. However, they are worth doing, because it enables us to summarize and make sense of the scientific progress that has been made, and point the way for future research. Finally, everyone needs to realize that this sort of work can only be accomplished in collaboration. In my research group, and also in international projects, good collaborations have to be established to enable excellent progress.

Professor Steve McGrath
Rothamsted Research
Rothamsted, Harpenden, Hertfordshire
United Kingdom

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