The ecotoxicological effects in the field can be directly assessed by measuring the concentration of the pollutant in soil or plant samples, and also by measuring response variables such as biochemical ones. However, there are few such studies integrating data on pollutants and plant biochemical variables and there is a knowledge gap about how dominant species in various ecological contexts respond in all their plant parts to heavy metal stress by changing biochemical variables. In this context, the objective of the research reported here is to describe how select biochemical variables varied in three plant parts of three plant species sampled from two areas with different levels of pollution. It was also of interest to identify to what extent they could be used in the non-destructive routine monitoring of pollution in industrial areas. We found a systematic decrease of chlorophylls and carotenoids in the aboveground parts of all species, and an increase of protein concentrations in all species and plant parts coupled with a decrease of superoxide dismutase and peroxidase activity. Although these patterns were correlated with a decrease of toxic element concentrations, both as pseudo- total and available forms in all plant parts, we cannot conclude that only a change in toxic elements pollution led to the observed patterns, because P nutrition also differed between plants. A further key direction of research is to clarify how the available major nutrients (N, P) modulate bioaccumulation of toxic elements and what effects they might have on biochemical variables of plants, in particular on oxidative stress.