I don't think there is one.

The icebergs that are melting are adding fresh or unsalty water to the ocean.

Icebergs that break off into the ocean from glaciers do not contain salt, as they are formed by freshwater on land (snow, ice).

Icebergs that form in the ocean mostly do not contain salt either. This is because as the seawater freezes, it forms a crystal structure (ice) that prevents salt ions from being included.

http://www.answers.com/Q/Do_icebergs_contain_sal

I suppose the salt we would put in would not change the proportion of the salt in the ocean all that much. A lot of the water we use goes right back into the ocean. We are on the coast.

What is storm water pollution?

Storm water pollution is when water from rainstorms, garden hoses and sprinklers causes runoff that collects harmful debris and flows through local creeks, rivers and lakes - eventually draining, untreated, into the ocean.
. . . .
Los Angeles is located in four watersheds - Los Angeles River, Ballona Creek, Dominguez Channel and Santa Monica Bay. The water from these four watersheds flows into San Pedro and Santa Monica Bays and ultimately into the Pacific Ocean.
. . . .
Storm water flows do not receive any treatment because of the sheer volume of runoff – tens of millions of gallons on even the driest day – from an area encompassing more than 1,000 square miles.
. . . .

The sanitary sewer system takes waste water from toilets, showers and sinks and routes it to one of several waste water treatment plants here in Los Angeles. Once there, it receives multiple levels of treatment before being discharged into the ocean.

more

http://www.lastormwater.org/about-us/frequently-asked-questions/

We put a lot of water that is salty in the ocean, so if we put salt in it too, I suppose it won't be such a problem.