Battling 30mph winds Burnell overcame the cold conditions to finish in fourth place overall, the top-ranked British male.
Craig Hamilton was the next British male to cross the line and puts himself in contention for World University Games with his sixth place finish. He beat fellow Brits, Tom Sunter, who finished seventh, and
Caleb Hughes who was one place further back in eighth.
Of Britain's women Danielle Huskisson was the highest finisher, crossing the line in 11th, one place ahead of compatriot Lucy Campbell while Lauren Walton was 15th.
Elsewhere Oliver Bitowt was 13th, Alice Dearing finished 17th and Philippa Shuttleworth was 21st.
Head coach Graham Bassi said: "The swimmers did a fantastic job this weekend, swimming in really very difficult conditions, they were really professional and it was an excellent team effort.
"Jack Burnell used his experience to stick with the pack and secure the top British spot at the finish but Caleb showed fantastic potential leading until the 7.5km mark.
"We were really impressed with Danielle Huskisson finishing 11th in her first open water international.
"The conditions were really difficult for the swimmers, it was 13 degrees and the final 500m were through 1-2ft waves into a head wind so we were immensely proud of everyone."