Concurrent plant uptake of heavy metals and persistent organic pollutants from soil

Abstract

The extent of anthropogenic environmental pollution—in the United States (Black, 1999; Glass, 1999), in the European Union (Chaudhry et al., 2002), and in the third world is well documented. For example, the Food and Agriculture Organization of the United Nations has estimated that at a minimum 10 t of unwanted pesticides are in ‘‘storage’’ in undeveloped countries, with at least 2 10 t in African countries (Chaudhry et al., 2002). The potential for negative impacts of these stocks on humans and the environment is of major concern. In situ remediation techniques, such as phytoremediation— the attenuation of pollution through the use of plants—which impose minimal environmental disturbance, offer economic, agronomic, and societal benefits to all countries. Up to the present time phytoremediation of soilborne heavy metals and of organic contaminants has been pursued as two distinct disciplines. This compartmentalized approach applies to fundamental studies of the mechanisms of action, as well as to the development of remediation technologies. Based on data from the authors’ laboratories over the preceding several years we propose that far more convergence as opposed to divergence in the underlying plant physiology and soil science impacts the soil/vegetation microcosm to attenuate both soil-borne heavy metals and organic pollutants. For example, our published research has established that zucchini (Cucurbita pepo L.) and spinach (Spinacia oleracea) bioaccumulate soil-bound persistent organic pollutants (POPs) (Mattina et al., 2002). Other published reports have shown that spinach bioaccumulates heavy metals from soil (Romer and Keller, 2001). The data which are presented here demonstrate that these two plants simultaneously bioconcentrate and translocate both categories of weathered, soil-bound pollutant. Such simultaneous uptake and translocation of heavy metal and organic pollutants, if confirmed and optimized, could have enormous implications for plant/soil interaction mechanisms, and impact on practical remediation approaches, and ultimately on risk to human health.