Higher amounts of PCB are often found in the deposited fine material of rivers or ports . At this places only a few plants are able to settle. The PCB have to be transfered through the barrier of the parachym of the plant into the inner tissue. The plant do not like it and pass away.

This paper might be of help/interest here

http://www.sciencedirect.com/science/article/pii/004565359290172N

Some literature says accumulation of PCB-5 in the root retrials. Phytoextraction contributed insignificantly toward the loss of the soil-borne PCB-5. Also hytoremediation prosses is described to remove the PCBs from soil (Chemosphere. 2011 Aug;84(7):943-9. doi: 10.1016/j.chemosphere.2011.06.007. Epub 2011 Jul 2.). But it is very difficult to explain the absorption mechanism. How ever, remediation of PCB by plants is often slow and incomplete. Also it is not clear this absorption is related to their nutrient absorption process. Testing of faty tissues of plan is very important to take a Idea .

The accumulation of PCB in terrestrial plants from contaminated soil are examined. But I think that the question of Adam refers to hydrophytes of the oceans.

PCBs are persistent organo-pollutants and because of their highly lipophilic nature might not accumulate substantially in producers (Aquatic or terrestrial plants) but possibly will bioaccumulate in those organisms higher up the food chain through the phenomenon of biomagnification. Adam, probably, you can roughly estimate these pollutants in plants indirectly by measuring their levels in organisms at the top of the food chain, then working backwards you determine their concentration in the producers, since the concentration of these pollutants increases by a constant factor as you move up the food chain.

This is a fascinating question. There appears to be real compound/species-specific uptake mechanisms at work POPs/plants...especially where the PBDEs are concerned. Several researchers (e.g. Vrkoslavova et al. cited above) have reported low to modest PBDE uptake in plants, but as many studies have reported none to negligible uptake. We have just submitted a paper to Environ. Sci. Technol. describing our findings of substantial PBDE accumulation in an agroecosystem receiving long-term wastewater sludge amendments containing mg/kg levels of both compound classes. We found substantial PBDE accumulation within virtually all biotic components of the sludge-impacted soil food web (inclusive of diverse soil arthropod taxa), but we did not detect PBDEs in the resident/dominant vegetation (gammagrass). And, though our major study focus here was sludge-associated PBDE accumulation, we did exam PCB accumulation in all sample types ancillary to this focus. Similarly, we found no PCB accumulation in the gamma grass. As some researchers have reported PCB translocation in plants, this again suggests that important compound/species-specific uptake mechanisms are at work. Fascinating topic indeed!

There are plants suitable for this, like alfa alfa and there is research conducted on this. If you are more specific on the compounds you are searching for, you might find more specific articles. I think PCBs with higher molecular weight than PCB-2 or PCB-3 are more recalcitrant towards phytoremediation.

While the statement "little to no PCBs are found in plants." is generally true, it is also true that PCB uptake into living systems is congener- and species-specific. One of the problems in assessing PCB uptake into plants is being able to discriminate between PCBs in soils, those that deposit and adhere to plant surfaces (typically ultra-fine particulate) and those that are selectively absorbed into the plant. It is reasonable to presume that the selective uptake of any compound will be regulated/limited by mechanisms within the plant (both passive and active) that are apparent in the "natural" un-impacted environment. For a PCB congener to get within a plant, it must enter through such mechanisms.

I worked as an aquatic/soils chemist for a few years. We tested PCB's in fish, plants, vegetables and everything else we could test. Some of the highest readings for some PCB congeners were plants that were watered with contaminated water.