CSX Corp. of Richmond, the new holding company for Chessie System and Seaboard Coast Line railway systems, yesterday reported consolidated 1980 profits of $281.6 million ($7.01 a share) on revenues of $4.8 billion.

In separate reports yesterday, American Security Corp., Virginia National Bankshares and Citizens Bank & Trust of Maryland all reported record earnings in 1980, which was a banner year for regional banking institutions.

The new CSX, which also owns extensive real estate and natural resources subsidiaries, said earnings were reduced by one-time merger-related accounting adjustments of $20.4 million (51 cents) and noted that if Chessie System and Seaboard Coastline Industries had reported separately, each would have posted a second consecutive year of record profits.

In 1979, Chessie had listed profits of $120.5 million on revenues of $1.86 billion while SCL earned $132.6 million on revenues of $2.17 billion.

CSX controls the Chesapeake & Ohio, Baltimore & Ohio, Western Maryland, Seaborad Coast Line, Louisville & Nashville, and Richmond, Fredericksburg & Potomac rail lines; Fruit Growers Express Co.; the currently-struck Greenbrier resort in West Virginia and newspaper in Florida.

Transportation revenues, which account for the largest business segment, rose about 12 percent from the previous year to $4.5 billion. CSX coal shipping hit record levels of 229 million tons, up 9 percent.

American Security Corp. owner of American Security Bank in Washington, reported a 12 percent increase in 1980 operating profits to $24.4 million ($6.77 a share) compared with $21.7 million (5.97) the previous year, despite a slight fourth-quarter decline. The 12 percent increase for the year matched that of ASB's arch-rival, Riggs National Bank, which had a stronger final quarter.

In the fourth quarter, American Security operating profits (not counting gains or losses from selling securities) declined to $6.14 million from $6.22 million ($1.71 a share in both periods). Net income for the year was $23.8 million ($2.25) vs. $21.5 million ($2.15) in 1979.

Chairman W. Jarvis Moody attributed the 1980 yearly gains to increased interest revenues on earning assets, in a period of interest-rate volatility. Assets rose 17 percent during the year to $2.7 billion, deposits were up 16 percent to $2.1 billion and loan volume rose by 8 percent to $1.5 billion.

Vriginia National Bankshares Inc., a Norfolk-based bank holding company, said 1980 operating profits rose 10 percent to $23.4 million. ($3.35 a share) compared with $21.3 million ($3.13) the previous year. Fourth-quarter operating profits increased 19 percent to $6.7 million (95 cents) from $5.6 million (83 cents).

Chairman C. A. Cutchins, III said VNB's gains came at a time of "instability of money-market interest rates and the unusually high level of inflation experienced throughout the year." The rapid rise in rates ws a major contributing factor to the substantial fourth-quarter gain in profits, VNB stated.

Statewide deposits rose to $2.17 billion from $2.08 billion while assets rose to $2.7 billion from $2.5 billion and loans were flat at $1.5 billion.

Citizens Bank & Trust, based in Riverdale, reported record 1980 profits (before and after securities transactions) of $9.6 million ($6.81 a share) compared with $9.4 million ($6.69) the prior year. An unusually strong fourth quarter contributed to the gain, as Citizens earned $2.03 a share compared with $1.48.

Assets rose 4 percent to $631 million and deposits increased by 3 percent to $543.5 million. Chairman Alfred H. Smith pointed out that interest the bank paid on time-deposits jumped $6.46 million during the year to $21.4 million, accounting for a substantial hike in operating expenses.

Central National Bank of Maryland, based in Silver Spring, posted a 17 percent increase in operating profits to $509,613 ($2.14 a share) compared with $433,638 ($1.86) in 1979. Assets rose 22 percent to $70 million while deposits increased by 22 percent to $63 million. Directors approved a cash dividend of 30 cents a share as well as a 5 percent stock dividend, paid on Jan. 7.