Activists are trying to blunt any proposal to locate a minor league baseball stadium in a section of Richmond that was a lucrative center for the slave trade leading to the Civil War. They are scheduled Monday to outline their opposition to the ballpark in the city’s Shockoe Bottom, which was second only to New Orleans as a slave-trading center. The opponents are fearful Mayor Dwight Jones will propose a stadium in the historic district to replace The Diamond, the home of the Richmond Squirrels. The ballpark is located in an industrial area. Opponents of the Shockoe Bottom stadium say the district is “sacred ground” that instead should be promoted as a heritage tourism destination. Activists say a broad coalition opposes a Shockoe Bottom stadium, including university professors and historians.