LONDON — Copper contract trading volumes on the London Metal Exchange fell in October, marking the third consecutive month that volumes have dropped on a year-on-year basis.

Copper contract trading volumes fell to 2.69 million lots in October, down 13.8 percent from 3.12 million lots in September and nearly 17 percent below the almost 3.24 million lots traded in October 2011.

The October volume is the second-lowest level this year and is 11.2 percent below the average monthly volume of 3.03 million lots seen so far in 2012.

Copper prices fell more than 5 percent during the month to levels seen prior to the Federal Reserve’s third round of quantitative easing, announced in early September.

Aluminum trading volumes also dropped on a year-on-year basis, but there were strong gains in other base metal contracts. Nickel and zinc volumes both jumped nearly 40 percent year on year to 1.06 million lots and 2.87 million lots, respectively.

Stronger volumes were also seen in lead and tin, while cobalt volumes—at 507 lots—rose 3.8 percent from October last year but fell 71.1 percent from September.

Across all futures contracts, trading volumes totaled 13.26 million lots in October, up from 12.76 million lots in the same month a year earlier but down about 355,000 lots from September.