:: Normaly heavy metals are present as unsoluble sulfides or oxides and therefor are not mobile in the water ( ground water ), by leaching you mobilize them.
परिभाषा
not easily solved; "an apparantly insolvable problem"; "public finance...had long presented problems unsolvable or at least unsolved"- C.L.Jones पर्याय: insolvable, unsolvable, unresolvable,
मोबाइल