About 100 litres of a chemical leaked into the Brisbane River from an on-shore container at Pinkenba Wharf overnight.

Emergency services were called to Tingira Street in Pinkenba, in Brisbane's north-east, just after 6.30pm on Thursday after a "slow leak" was discovered, according to the fire service.

Pinkenba Wharf on the Brisbane River. Credit:Google Maps

Firefighters found the leaking valve, contained the spill and wrapped up about 9.30pm.

Police said the chemical involved was styrene monomer, used in the making of plastics.