Carbon as a slight affinity for metals, but not much. I've looked mostly at Arsenic (flavor of the local water and something I encounter in various spots in the Far- and Mountain-west USA) and carbon does reduce it a bit, but the % removal is small even in large-capacity carbon vessels (one-day residence time) that I use for work.
For metals, typically we use an ion-exchange resin. It is highly effective, and occurs quickly, but I'm not aware of a small-scale version. If one posed as an engineer doing a feasibility study and talked Westates or Calgon or some other vendor out of a pound or two, you'd be set for life but often they want you to send them many liters of the water and they conduct a bench-scale test to generate design specs.
Other options for metals are distillation and reverse osmosis. Either of which you might do for drinking water at home or cruising on a sailboat but never while backpacking.
I'd note though, that a microgram of infectious stuff breeds in your body and can make you quite sick from one exposure. While cancinogens and toxics are dose-related - more exposure is worse, less exposure is less risk. If you live in Fallon Nevade - TREAT YOUR WATER FOR ARSENIC!!!, but if you are just passing through, you'll have 1/365 x 1/70 the risk of a life-long resident.
UL for metals (and sorry, this is a campsite technique, not while hiking): a pinch of baking soda to raise the pH (acidified water dissolves MUCH more metal) and a pinch of alum (which can be bought cheaply in small quantity in very well-stocked bulk food / spice departments of health food stores). The alum allows all sorts of stuff to flouculate (clump together) and sink or rise in a water. The alum is edible - it is used in some cooking. It is amazing to compare side-by-side Colorado River water with and without alum for settling times - there's an easy 10-fold difference AND the alum-treated water is MUCH clearer of silt, metals, etc. Then skim the scum off the top and decant the clear liquid without disturbing the sediments on the bottom. Biological matter will also have tended to sink or rise, so the clear liquid will have a MUCH lower biological load, but while this would greatly reduce your bio exposure, it shouldn't be considered 99.99% effective like a good filter would be. (Your filter, will however, go MUCH longer between cleanings if you settle out the crud first).